Process for dyeing keratin fibres using at least one particular 2- or 4-azopyridinium dye and at least one fluorescent dye

ABSTRACT

The present invention relates to a process for dyeing keratin fibres, in particular human keratin fibres such as the hair, using one or more particular 2- or 4-azopyridinium dyes and one or more fluorescent dyes. The present invention also relates to a cosmetic composition comprising the dyes defined above, and also to a multi-compartment device containing said dyes. The present invention also relates to the use of said dyes for dyeing light keratin fibres, especially human keratin fibres such as the hair, in chestnut-brown, dark chestnut-brown, brown, brown with a glint, or even black, without using an additional dye other than those defined above.

The present invention relates to a process for dyeing keratin fibres, inparticular human keratin fibres such as the hair, using one or moreparticular 2- or 4-azopyridinium dyes and one or more fluorescent dyes.

The present invention also relates to a cosmetic composition comprisingthe dyes defined above, and also to a multi-compartment devicecontaining said dyes.

The present invention also relates to the use of said dyes for dyeinglight keratin fibres, especially human keratin fibres such as the hair,in chestnut-brown, dark chestnut-brown, brown, brown with a glint, oreven black, without using an additional dye other than those definedabove.

Many people have sought for a long time to modify the colour of theirhair and in particular to mask their grey hair.

It is especially known practice to dye keratin fibres, in particularhuman keratin fibres, with dye compositions containing oxidation dyeprecursors, which are generally known as oxidation bases. Theseoxidation bases are colourless or weakly coloured compounds, which, whencombined with oxidizing products, may give rise to coloured compoundsvia a process of oxidative condensation.

The shades obtained with these oxidation bases may be modified bycombining them with couplers or colour modifiers. The variety ofmolecules used as oxidation bases and couplers allows a wide range ofcolours to be obtained.

Another well-known method consists in obtaining semi-permanent dyeing byapplying to the keratin fibres direct dyes, which are coloured andcolouring molecules that have affinity for said fibres.

The direct dyes conventionally used are chosen from nitrobenzene,anthraquinone, nitropyridine, azo, xanthene, acridine, azine andtriarylmethane direct dyes. The chemical species may be nonionic,anionic (acidic dyes) or cationic (basic dyes). The direct dyes may alsobe natural dyes.

Conventional direct dyeing processes consist in applying to keratinfibres dye compositions comprising direct dyes. After application, aleave-on time is observed so as to allow the colouring molecules topenetrate by diffusion into the fibres. On conclusion of the process,the fibres are rinsed.

In contrast with oxidation dyeing, these direct dyeing processes have atendency to better protect the integrity of the fibres. The resultingcolourings are generally chromatic, but, however, are onlysemi-temporary. The nature of the interactions that bind the direct dyesto the keratin fibres and their desorption from the surface and/or thecore of the fibre are responsible for their weak dyeing power.

Although a wide range of colours is currently accessible, it generallyproves necessary to combine three dyes of complementarycolours—trichromatic principle—in order to obtain a natural shade (see,for example, WO 95/15144 and WO 95/01772). This tripartite combinationdoes not, however, show good persistence with respect to repeatedshampooing. It generally, or even systematically, induces an unaestheticchanging of the colour, which the consumer finds dissuasive.

These colourings are furthermore not sufficiently fast in the face ofexternal agents such as light or perspiration.

Thus, there is a real need to develop processes for the direct dyeing ofkeratin fibres, in particular of human keratin fibres such as the hair,which do not have the drawbacks mentioned above, i.e. which make itpossible especially to lead to natural colourings that have goodproperties, especially in terms of chromaticity, power, intensity, sheenand selectivity, and which are persistent with respect to shampooing.

Another aim of the present invention is thus to be able to dye lightkeratin fibres efficiently in chestnut-brown, dark chestnut-brown, brownor brown with a glint or even black, by mixing direct dyes, andpreferably only two types of direct dye.

The Applicant has found, surprisingly, that a process for dyeing keratinfibres using one or more particular 2- or 4-azopyridinium dyes and oneor more fluorescent dyes makes it possible to achieve the objectivesmentioned above; especially to lead to natural chestnut-brown, darkchestnut-brown, brown, brown with a glint or even black colourings,which are not only powerful and shiny, but also shampoo-resistant.

One subject of the present invention is especially a process for dyeingkeratin fibres, in particular human keratin fibres such as the hair,comprising the application to said keratin fibres of the followingingredients: (a) one or more 2- or 4-azopyridinium dyes chosen from thecompounds of formula (I) or (II) below, the optical isomers thereof, thegeometrical isomers thereof, the tautomers thereof, the organic ormineral, acid or base salts thereof, the solvates thereof such ashydrates, and mixtures thereof,

in which formulae (I) and (II):

-   -   R₁ and R′₁, which may be identical or different, represent an        optionally substituted linear or branched C₁ to C₆ alkyl        radical;    -   R₂ and R′₂, which may be identical or different, represent:        -   a halogen atom, preferentially a chlorine atom, or        -   a linear or branched C₁ to C₄ alkyl radical;    -   R₃ and R′₃, which may be identical or different, represent,        independently of each other:        -   a C₁ to C₄ alkyl radical, preferably methyl or ethyl,        -   a (di)(C₁-C₄)(alkyl)amino radical,        -   a (C₁-C₄)alkylcarbonylamino radical, preferably acylamino            (—NHCOCH₃),        -   a hydroxyl radical,        -   a halogen atom, preferably a chlorine atom,        -   a C₁ to C₄ alkoxy radical, preferably methoxy or ethoxy,        -   a (C₁-C₄)alkylthio radical,        -   or alternatively, two adjacent radicals R₃ or R′₃ together            form a 6-membered aromatic ring optionally substituted with            one or more hydroxyl or amino groups;    -   R₄ and R′₄, which may be identical or different, represent:        -   a (di)(C₁-C₄)(alkyl)amino radical,        -   a hydroxyl radical,        -   a C₁ to C₄ alkoxy radical, preferably methoxy or ethoxy,        -   a radical —NR₅R₆, in which R₅ and R₆, which may be identical            or different, represent, independently of each other:            -   a linear or branched, optionally substituted C₁ to C₂₀                alkyl radical, or            -   a phenyl radical;        -   or alternatively, two radicals R₃ of formula (I) or R′₃ of            formula (II) located, respectively, ortho to the group R₄            (formula (I)) or R′₄ (formula (II)) form, respectively, with            R₅ and R₆ of the group R₄ (formula (I)) or of the group R′₄            (formula (II)) a 6- to 10-membered heterocycle optionally            comprising one or more heteroatoms, preferably the phenyl            group substituted with R₃ and R₄ or R′₃ and R′₄ represents a            julolidine group;    -   m, m′, n and n′ are integers ranging from 0 to 4;    -   Y represents an anionic counterion or a mixture of organic or        inorganic anions which ensure the electrical neutrality of the        compounds of formula (I) and/or (II); and (b) one or more        fluorescent dyes;        it being understood that the 2- or 4-azopyridinium dye(s) (a)        and the fluorescent dye(s) (b) are applied to said keratin        fibres together or sequentially.

Another subject of the invention is a cosmetic composition comprising:(a) one or more 2- or 4-azopyridinium dyes chosen from the compounds offormula (I) or (II) as defined previously, and also the optical isomersthereof, the geometrical isomers thereof, the tautomers thereof, theorganic or mineral, acid or base salts thereof, the solvates thereofsuch as hydrates, and mixtures thereof; and (b) one or more fluorescentdyes.

The combination of particular 2- or 4-azopyridinium dye(s) and offluorescent dye(s) makes it possible especially to obtain naturalcolourings that have good dyeing properties, especially in terms ofchromaticity, power, intensity, sheen and selectivity.

Furthermore, the process and the composition according to the inventionmake it possible to dye light keratin materials efficiently inchestnut-brown, dark chestnut-brown, brown, brown with a glint or evenblack, by mixing direct dyes, and in particular only the dyes (a) and(b) as defined previously, without the need to use an additional (orcomplementary) dye other than (a) or (b).

Moreover, the colourings obtained by means of the process and thecomposition according to the invention show good resistance to thevarious attacking factors to which the hair may be subjected, such aslight, bad weather, washing and perspiration. They are in particularpersistent with respect to shampooing, especially after at least threeshampoo washes.

A subject of the present invention is also a multi-compartment devicecomprising a first compartment containing one or more 2- or4-azopyridinium dyes (a) chosen from the compounds of formula (I) or(II) as defined previously, and also the optical isomers thereof, thegeometrical isomers thereof, the tautomers thereof, the organic ormineral, acid or base salts thereof, the solvates thereof such ashydrates, and mixtures thereof, and a second compartment containing oneor more fluorescent dyes (b) as defined previously.

Another subject of the invention is the use of fluorescent dye(s), asdefined previously, combined with 2- or 4-azopyridinium dye(s) chosenfrom the compounds of formula (I) or (II), as defined previously, andalso the optical isomers thereof, the geometrical isomers thereof, thetautomers thereof, the organic or mineral, acid or base salts thereof,the solvates thereof such as hydrates, and mixtures thereof, for thedyeing of light keratin fibres, especially human keratin fibres such asthe hair, in chestnut-brown, dark chestnut-brown, brown, brown with aglint or even black, without using an additional dye other than (a) or(b).

Other subjects, characteristics, aspects and advantages of the inventionwill emerge even more clearly on reading the description and theexamples that follow.

For the purposes of the present invention and unless otherwiseindicated:

-   -   the “dyes” according to the invention absorb light in the        visible range, i.e. at a wavelength λ_(abs) particularly of        between 400 and 700 nm inclusive;    -   for the purposes of the present invention, the term “direct dye”        means natural and/or synthetic dyes, which are soluble in the        cosmetic medium, other than oxidation dyes; they are dyes which        will diffuse superficially on the keratin fibres;    -   for the purposes of the present invention, the term “fluorescent        dye” means a dye which is a coloured molecule (which absorbs        visible light) and which itself imparts colour, and which, in        contrast with a conventional dye, transforms the absorbed energy        into light of a longer wavelength emitted in the visible part of        the spectrum; in particular, the “fluorescent” dyes of the        invention are capable of absorbing light in the visible range at        a wavelength λ_(abs) of between 350 and 800 nm and of        re-emitting in the visible range at a longer wavelength λ_(em)        than that absorbed, of between 400 and 800 nm; the difference        between the absorption and emission wavelengths, also known as        the Stoke's shift, is between 1 nm and 100 nm. More        preferentially, the fluorescent dyes of the invention are dyes        that are capable of absorbing at a wavelength λ_(abs) of between        420 nm and 550 nm and of re-emitting in the visible range at a        wavelength λ_(cm) of between 470 and 600 nm;    -   the “fluorescent dyes” according to the present invention are to        be differentiated from optical brighteners. Optical brighteners,        also known as “brighteners” or “fluorescent brighteners” or        “fluorescent brightening agents” or “fluorescent whitening        agents or FWA” or “whiteners” or “fluorescent whiteners”, are        colourless compounds, which do not impart a colour and are        consequently not dyes since they do not absorb in the visible        light range, but only absorb in the ultraviolet range        (wavelength ranging from 200 to 400 nm) and transform the        absorbed energy into fluorescent light of a longer wavelength        emitted in the visible part of the spectrum in the blue range.        The colour impression is then generated only by the purely        fluorescent light that is predominantly blue (wavelength ranging        from 400 to 500 nm).    -   the “blue, violet and green” dyes according to the invention are        dyes which absorb light in the visible spectrum and which appear        blue visually, i.e. which absorb light at an absorption        wavelength λ_(max) greater than 550 nm and less than or equal to        700 nm, in particular λ_(max) between 560 nm and 700 nm,        preferably in the blue range, i.e. λ_(max) between 580 and 650        nm;    -   the term “(hetero)aryl” means aryl and heteroaryl groups;    -   the “aryl” or “heteroaryl” radicals or the aryl or heteroaryl        part of a radical may be substituted with at least one        substituent borne by a carbon atom, chosen from:    -   a C₁-C₆ and preferably C₁-C₄ alkyl radical optionally        substituted with one or more radicals chosen from hydroxyl,        C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, acylamino, amino        substituted with two C₁-C₄ alkyl radicals, which may be        identical or different, optionally bearing at least one hydroxyl        group, or the two radicals possibly forming, with the nitrogen        atom to which they are attached, a saturated or unsaturated,        optionally substituted 5- to 7-membered and preferably 5- or        6-membered heterocycle optionally comprising another nitrogen or        non-nitrogen heteroatom;    -   a halogen atom such as chlorine;    -   a hydroxyl or thiol group;    -   a C₁-C₆ alkoxy or C₁-C₆ alkylthio radical;    -   a (poly)hydroxy(C₂-C₆)alkoxy radical;    -   an amino radical;    -   a 5- or 6-membered heterocycloalkyl radical, preferentially        morpholino, piperazino, piperidino or pyrrolidino, which is        optionally substituted with a (C₁-C₄) alkyl radical,        preferentially methyl;    -   a 5- or 6-membered heteroaryl radical, preferentially        imidazolyl, optionally substituted with a (C₁-C₄)alkyl radical,        preferentially methyl;    -   an amino radical substituted with one or two identical or        different C₁-C₆ alkyl radicals, optionally bearing at least:    -   i) a hydroxyl group,    -   ii) an amino group optionally substituted with one or two        optionally substituted C₁-C₃ alkyl radicals, said alkyl radicals        possibly forming with the nitrogen atom to which they are        attached a saturated or unsaturated, optionally substituted 5-        to 7-membered heterocycle, optionally comprising at least one        other nitrogen or non-nitrogen heteroatom,    -   iii) a quaternary ammonium group —N+R′R″R″′, M⁻ for which R′, R″        and R″′, which may be identical or different, represent a C₁-C₄        alkyl group and M-represents an anionic counterion,    -   iv) or an optionally cationic 5- or 6-membered heteroaryl        radical, preferentially imidazolium, optionally substituted with        a (C₁-C₄)alkyl radical, preferentially methyl;    -   an acylamino radical (—N(R)—C(O)—R′) in which the radical R is a        hydrogen atom or a C₁-C₄ alkyl radical optionally bearing at        least one hydroxyl group and the radical R′ is a C₁-C₂ alkyl        radical;    -   a carbamoyl radical ((R)₂N—C(O)—) in which the radicals R, which        may be identical or different, represent a hydrogen atom or a        C₁-C₄ alkyl radical optionally bearing at least one hydroxyl        group;    -   an alkylsulfonylamino radical (R′—S(O)₂—N(R)—) in which the        radical R represents a hydrogen atom or a C₁-C₄ alkyl radical        optionally bearing at least one hydroxyl group and the radical        R′ represents a C₁-C₄ alkyl radical, or a phenyl radical;    -   an aminosulfonyl radical ((R)₂N—S(O)₂—) in which the radicals R,        which may be identical or different, represent a hydrogen atom        or a C₁-C₄ alkyl radical optionally bearing at least one        hydroxyl group;    -   a carboxyl radical in acid or salified form (preferably salified        with an alkali metal or a substituted or unsubstituted        ammonium);    -   a cyano group;    -   a nitro or nitroso group;    -   a polyhaloalkyl group, preferentially trifluoromethyl;    -   the cyclic or heterocyclic part of a non-aromatic radical may be        substituted with at least one substituent chosen from the        following groups:    -   hydroxyl;    -   C₁-C₄ alkoxy, (poly)hydroxy(C₂-C₄)alkoxy;    -   C₁-C₄ alkyl;    -   alkylcarbonylamino (R—C(O)—N(R′)—) in which the radical R′ is a        hydrogen atom or a C₁-C₄ alkyl radical optionally bearing at        least one hydroxyl group, and the radical R is a C₁-C₂ alkyl        radical or an amino radical optionally substituted with one or        two C₁-C₄ alkyl groups, which may be identical or different,        themselves optionally bearing at least one hydroxyl group, said        alkyl radicals possibly forming, with the nitrogen atom to which        they are attached, a saturated or unsaturated, optionally        substituted 5- to 7-membered heterocycle optionally comprising        at least one other nitrogen or non-nitrogen heteroatom;    -   alkylcarbonyloxy (R—C(O)—O—) in which the radical R is a C₁-C₄        alkyl radical or an amino group optionally substituted with one        or two identical or different C₁-C₄ alkyl groups themselves        optionally bearing at least one hydroxyl group, said alkyl        radicals possibly forming with the nitrogen atom to which they        are attached a saturated or unsaturated, optionally substituted        5- to 7-membered heterocycle, optionally comprising at least one        other nitrogen or non-nitrogen heteroatom;    -   alkoxycarbonyl (R—X—C(O)—) in which the radical R is a C₁-C₄        alkoxy radical, X is an oxygen atom or an amino group optionally        substituted with a C₁-C₄ alkyl group itself optionally bearing        at least one hydroxyl group, said alkyl radical possibly forming        with the nitrogen atom to which it is attached a saturated or        unsaturated, optionally substituted 5- to 7-membered        heterocycle, optionally comprising at least one other nitrogen        or non-nitrogen heteroatom;    -   a cyclic or heterocyclic radical, or a non-aromatic part of an        aryl or heteroaryl radical, which may also be substituted with        one or more oxo groups;    -   an “aryl” radical represents a monocyclic or fused or non-fused        polycyclic carbon-based group comprising from 6 to 22 carbon        atoms, at least one ring of which is aromatic; preferentially,        the aryl radical is a phenyl, biphenyl, naphthyl, indenyl,        anthracenyl or tetrahydronaphthyl;    -   a “cationic heteroaryl radical” is a heteroaryl group as defined        previously, which comprises an endocyclic or exocyclic cationic        group,        -   when the charge is endocyclic, it is included in the            electron delocalization via the mesomeric effect; for            example, it is a pyridinium, imidazolium or indolinium            group:

-   -   -   with R and R′ being a heteroaryl substituent as defined            previously and particularly a (hydroxy)(C₁-C₅)alkyl group,            such as methyl;        -   when the charge is exocyclic, it is not included in the            electron delocalization via the mesomeric effect; for            example, it is an ammonium or phosphonium substituent R⁺,            such as trimethylammonium, which is outside the heteroaryl,            such as pyridyl, indolyl, imidazolyl or naphthalimidyl, in            question:

-   -   -   with R being a heteroaryl substituent as defined below and            R⁺ an ammonium R_(a)R_(b)R_(c)N⁺—, phosphonium            R_(a)R_(b)R_(c)P⁺— or ammonium R_(a)R_(b)R_(c)N⁺—            (C₁-C₆)alkylamino, R_(a)R_(b)R_(c)N⁺—(C₁-C₆)alkyl or            R_(a)R_(b)R_(c)N⁺—(C₁-C₆)alkoxy group with R_(a), R_(b) and            R_(c), which may be identical or different, being a            (C₁-C₈)alkyl group such as methyl;

    -   a “heteroaryl radical” represents a 5- to 22-membered,        monocyclic or fused or non-fused polycyclic group, comprising        from 1 to 6 heteroatoms chosen from nitrogen, oxygen and sulfur,        at least one ring of which is aromatic; preferentially, a        heteroaryl radical is chosen from acridinyl, benzimidazolyl,        benzobistriazolyl, benzopyrazolyl, benzopyridazinyl,        benzoquinolyl, benzothiazolyl, benzotriazolyl, benzoxazolyl,        pyridinyl, tetrazolyl, dihydrothiazolyl, imidazopyridinyl,        imidazolyl, indolyl, isoquinolyl, naphthoimidazolyl,        naphthoxazolyl, naphthopyrazolyl, oxadiazolyl, oxazolyl,        oxazolopyridyl, phenazinyl, phenoxazolyl, pyrazinyl, pyrazolyl,        pyrilyl, pyrazoyltriazyl, pyridyl, pyridinoimidazolyl, pyrrolyl,        quinolyl, tetrazolyl, thiadiazolyl, thiazolyl,        thiazolopyridinyl, thiazoylimidazolyl, thiopyrylyl, triazolyl,        xanthylyl and the ammonium salt thereof;

    -   a “heterocyclic radical” is a radical which may contain one or        two unsaturations, but is a monocyclic or fused or non-fused        polycyclic, 5- to 22-membered non-aromatic radical comprising        from 1 to 6 heteroatoms chosen from nitrogen, oxygen and sulfur;

    -   a “heterocycloalkyl radical” is a heterocyclic radical        comprising at least one saturated ring;

    -   an “alkyl radical” is a linear or branched C₁ to C₂₀, preferably        C₁ to C₁₀, more preferentially C₁ to C₈, better still C₁ to C₆        and even better still C₁ to C₄ hydrocarbon-based radical;

    -   the expression “optionally substituted” applied to the alkyl        radical implies that said alkyl radical may be substituted with        one or more radicals chosen from the following radicals: i)        hydroxyl, ii) C₁-C₄ alkoxy, iii) R—Z—C(X)—Y— with X, Y and Z        representing an oxygen or sulfur atom or N(R′), or alternatively        X and/or Z represent a bond, R and R′, which may be identical or        different, represent a hydrogen atom or a (C₁-C₆)alkyl group,        preferably, X represents an oxygen atom, iv) amino optionally        substituted with one or two identical or different C₁-C₄ alkyl        radicals, said alkyl radicals possibly forming, with the        nitrogen atom that bears them, a 5- to 7-membered heterocycle,        optionally comprising another nitrogen or non-nitrogen        heteroatom; v) or a quaternary ammonium group N+R′R″R″′, M⁻ for        which R′, R″ and R″′, which may be identical or different,        represent a C₁-C₄ alkyl group, or alternatively —N⁺R′R″R″′ forms        a heteroaryl such as imidazolium optionally substituted with a        C₁-C₄ alkyl group and M⁻ represents the anionic counterion, vi)        carboxyl C(O)OH, vii) carboxylate C(O)O—, M⁺ with M⁺        representing a cationic counterion such as alkali metal or        alkaline-earth metal, viii) sulfonic —SO₃H, ix) sulfonate —SO₃        ⁻, M⁺ with M⁺ as defined previously, x) cyano and xi) phenyl;

    -   an “alkoxy radical” is an alkyl-oxy radical for which the alkyl        radical is a linear or branched C₁-C₈ and preferentially C₁-C₆        hydrocarbon-based radical;

    -   when the alkoxy group is optionally substituted, this implies        that the alkyl group is optionally substituted as defined above;

    -   the term “organic or mineral acid salt” more particularly means        the salts chosen from a salt derived from i) hydrochloric acid        HCl, ii) hydrobromic acid HBr, iii) sulfuric acid H₂SO₄, iv)        alkylsulfonic acids: Alk-S(O)₂OH such as methanesulfonic acid        and ethanesulfonic acid; v) arylsulfonic acids: Ar—S(O)₂OH such        as benzenesulfonic acid and toluenesulfonic acid; vi) citric        acid; vii) succinic acid; viii) tartaric acid; ix) lactic        acid; x) alkoxysulfinic acids: Alk-O—S(O)—OH such as        methoxysulfinic acid and ethoxysulfinic acid; xi)        aryloxysulfinic acids such as tolueneoxysulfinic acid and        phenoxysulfinic acid; xii) phosphoric acid H₃PO₄; xiii) acetic        acid CH₃C(O)—OH; xiv) triflic acid CF₃SO₃H; and xv)        tetrafluoroboric acid HBF₄;

    -   the term “anionic counterion” means an anion or an anionic group        derived from an organic or mineral acid which counterbalances        the cationic charge of the dye; more particularly, the anionic        counterion is chosen from: i) halides such as chloride or        bromide; ii) nitrates; iii) sulfonates, including C₁-C₆        alkylsulfonates: Alk-S(O)₂O⁻ such as methylsulfonate or mesylate        and ethylsulfonate; iv) arylsulfonates: Ar—S(O)₂O⁻ such as        benzenesulfonate and toluenesulfonate or tosylate; v)        carboxylates Alk-C(O)—OH with Alk representing a (C₁-C₆)alkyl        group optionally substituted with one or more hydroxyl or        carboxylate groups such as citrate; vi) succinate; vii)        tartrate; viii) lactate; ix) alkyl sulfates: Alk-O—S(O)O⁻ such        as methyl sulfate and ethyl sulfate; x) aryl sulfates:        Ar—O—S(O)O⁻ such as benzene sulfate and toluene sulfate; xi)        alkoxy sulfates: Alk-O—S(O)₂O⁻ such as methoxy sulfate and        ethoxy sulfate; xii) aryloxy sulfates: Ar—O—S(O)₂O⁻, xiii)        phosphates O═P(OH)₂—O⁻, O═P(O⁻)₂—OH, O═P(O⁻)₃,        HO—[P(O)(O⁻)]_(w)—P(O)(O⁻)₂ with w being an integer; xiv)        acetate; xv) triflate; and xvi) borates such as        tetrafluoroborate, and xvii) sulfate (O=)₂S(O⁻)₂ or SO₄ ²⁻ and        hydrogen sulfate HSO₄ ⁻;

    -   the anionic counterion, derived from the organic or mineral acid        salt, ensures the electrical neutrality of the molecule; thus,        it is understood that when the anion comprises several anionic        charges, then the same anion may serve for the electrical        neutrality of several cationic groups in the same molecule or        else may serve for the electrical neutrality of several        molecules; for example, a dye which contains two cationic groups        may contain either two “singly charged” anionic counterions or a        “doubly charged” anionic counterion such as (O═)₂S(O⁻)₂ or        O═P(O⁻)₂—OH;

    -   In particular, the anionic counterions are chosen from halides        such as chloride, bromide, fluoride or iodide; a hydroxide; a        sulfate; a hydrogen sulfate; a linear or branched C₁-C₆ alkyl        sulfate, such as the methyl sulfate or ethyl sulfate ion;        carbonates and hydrogen carbonates; carboxylic acid salts such        as formate, acetate, citrate, tartrate and oxalate; linear or        branched C₁-C₆ alkylsulfonates, such as the methylsulfonate ion;        arylsulfonates for which the aryl part, preferably phenyl, is        optionally substituted with one or more C₁-C₄ alkyl radicals,        for instance 4-tolylsulfonate; and alkylsulfonates such as        mesylate;

    -   The term “chemical oxidizing agent” means any oxidizing agent        other than atmospheric oxygen conventionally used in the field.        Thus, mention may be made of hydrogen peroxide, urea peroxide,        alkali metal bromates, persalts such as perborates and        persulfates, and also enzymes, among which mention may be made        of peroxidases, 2-electron oxidoreductases such as uricases, and        4-electron oxygenases such as laccases. Preferably, the chemical        oxidizing agent is hydrogen peroxide;

    -   Moreover, the addition salts that may be used in the context of        the invention are especially chosen from salts of addition with        a cosmetically acceptable base such as the basifying agents as        defined below, for instance alkali metal hydroxides, such as        sodium hydroxide or potassium hydroxide, aqueous ammonia, amines        or alkanolamines;

    -   the expression “at least one” is equivalent to “one or more”;

    -   the limits of a range of values are included in that range, in        particular in the expressions “between” and “ranging from . . .        to . . . ”; and

    -   the expression “inclusive” for a range of values means that the        limits of that range are included in the defined range.

    -   (a) 2- or 4-azopyridinium Dyes

The process for dyeing keratin fibres and the cosmetic compositionaccording to the present invention use, or comprise, (a) one or more 2-or 4-azopyridinium dyes chosen from the compounds of formula (I) or (II)as defined previously, the optical isomers thereof, the geometricalisomers thereof, the tautomers thereof, the organic or mineral, acid orbase salts thereof, the solvates thereof such as hydrates, and mixturesthereof.

In particular, the dyes of formula (I) or (II) are blue, violet orgreen, and dull or chromatic.

When m, m′, n and n′ are less than 4, then the remaining carbon atom(s)are substituted with a hydrogen atom.

Preferably, R₁ and R′₁, which may be identical or different, represent alinear C₁ to C₆ alkyl radical, optionally substituted with one or morehydroxyl groups, and more preferentially a linear C₁ to C₆ alkyl group,optionally substituted with a hydroxyl group, such as a methyl, hexyl orhydroxyhexyl group.

Preferably, m and m′ are equal to 0 or 1, and R₂ and R′₂, independentlyof each other, represent a chlorine atom or a methyl group.

Preferably, R₄ and R′₄, which may be identical or different, represent:

-   -   an amino radical, or    -   a radical —NR₅R₆, in which R₅ and R₆, which may be identical or        different, represent, independently of each other:    -   a linear or branched C₁ to C₆ and more preferentially C₁ to C₄        alkyl radical, optionally substituted with one or more hydroxyl        groups, or    -   a phenyl radical.

According to a particular embodiment, R₁, R′₁, R₂, R′₂ and Y are asdefined previously, and

-   -   R₃ and R′₃, which may be identical or different, represent,        independently of each other:        -   a C₁ to C₂ alkyl radical,        -   an amino radical,        -   an acylamino radical (—NHCOCH₃),        -   a chlorine atom,        -   a C₁ to C₂ alkoxy radical,        -   or alternatively, two adjacent radicals R₃ or R′₃ together            form a 6-membered aromatic ring optionally substituted with            a hydroxyl or amino group,        -   or alternatively, two radicals R₃ of formula (I) or R′₃ of            formula (II) located, respectively, ortho to the group R₄            (formula (I)) or R′₄ (formula (II)) form, respectively, with            R₅ and R₆ of the group R₄ (formula (I)) or of the group R′₄            (formula (II)) a 6- to 10-membered heterocycle comprising            one or two heteroatoms such as nitrogen, preferably the            phenyl group substituted with R₃ and R₄ or R′₃ and R′₄            represents a julolidine group; and    -   R₄ and R′₄, which may be identical or different, represent:    -   an amino radical, or    -   a radical —NR₅R₆, in which R₅ and R⁶, which may be identical or        different, represent, independently of each other:        -   a linear or branched C₁ to C₄ alkyl radical, optionally            substituted with one or more hydroxyl groups, or        -   a phenyl radical.

Advantageously, Y is an anionic counterion as defined previously.

The compounds of formula (I) or (II) may also be in the form ofsolvates, for example a hydrate or a solvate of a linear or branchedalcohol such as ethanol or isopropanol.

Preferably, the 2- or 4-azopyridinium dye(s) are chosen from thefollowing compounds, the optical isomers thereof, the geometricalisomers thereof, the tautomers thereof, the organic or mineral, acid orbase salts thereof, the solvates thereof such as hydrates, and mixturesthereof:

Y being as defined previously.

More preferentially, the 2- or 4-azopyridinium dye(s) are chosen fromthe following compounds, the optical isomers thereof, the geometricalisomers thereof, the tautomers thereof, the organic or mineral, acid orbase salts thereof, the solvates thereof such as hydrates, and mixturesthereof:

According to a particular embodiment, the dye(s) (a) are chosen from the2-azopyridinium compounds of formula (II) as defined above. Morepreferentially, the dye(s) (a) are chosen from compounds (1) to (20).

According to another particular embodiment, the dye(s) (a) are chosenfrom the 4-azopyridinium compounds of formula (I) as defined above.According to this embodiment, the dye(s) (a) are preferably chosen fromcompounds (21) to (27), more preferentially (21a)-(27a), and betterstill the dye(s) (a) are chosen from compounds (21b), (23b), (26a) and(27a).

(b) Fluorescent Dyes

The process for dyeing keratin fibres and the composition according tothe present invention also use, or comprise, (b) one or more fluorescentdyes.

Preferably the fluorescent dye(s) of the invention are direct dyes. Moreparticularly, the fluorescent dye(s) of the invention are other thanfluorescent dyes comprising a disulfide bond. More preferentially, thefluorescent dye(s) of the invention are direct dyes and do not comprisea bond containing contiguous identical heteroatoms.

As fluorescent dyes that may be used in the present invention, mentionmay be made of the following dyes: acridines, acridones, azlactones,benzanthrones, benzimidazoles, benzimidazolones, benzindoles,benzoxazoles, benzopyrans, benzothiazoles, coumarins, difluoro{2-[(2H-pyrrol-2-ylidene-kN)methyl]-1H-pyrrolato-kN}borons (BODIPY®),dipyrinones, diketopyrrolopyrroles, fluorindines, (poly)methines(especially cyanins and styryls/hemicyanins), naphthalimides,naphthanilides, naphthylamine (such as dansyls), naphtholactams,oxadiazoles, oxazines, perilones, perinones, perylenes,polyenes/carotenoids, squaranes, stilbenes, xanthenes, thioxanthenes,thiazines, and mixtures thereof.

Mention may also be made of the fluorescent dyes described in EP 1 133975, WO 03/029 359, EP 860 636, WO 95/01772, WO 95/15144, EP 714 954 andthose listed in the encyclopaedia The chemistry of synthetic dyes by K.Venkataraman, 1952, Academic Press, vol. 1 to 7, in Kirk Othmer'sencyclopaedia Chemical Technology, in the chapter “Dyes and DyeIntermediates”, 1993, Wiley and Sons, and in various chapters ofUllmann's Encyclopedia of Industrial Chemistry, 7th edition, Wiley andSons, especially in Ullmann's Encyclopedia of Industrial Chemistry inthe chapter “Fluorescent Dyes”, 2005, Wiley-VCH Verlag GmbH & Co. KGaA,Weinheim 10.1002/143560007.all 279; in The Handbook—A Guide toFluorescent Probes and Labeling Technologies, 10th Ed MolecularProbes/Invitrogen—Oregon 2005 circulated by Internet or in the precedingprinted editions.

Preferably, the fluorescent dye(s) (b) of the invention are chosen fromcoumarin dyes, (poly)methine dyes, in particular cyanin andstyryl/hemicyanin dyes, and naphthalimide dyes.

More particularly, the fluorescent dye(s) of the invention are cationic.

Preferably, the fluorescent dye(s) of the invention are direct dyeschosen from (poly)methine dyes, in particular cyanin dyes andstyryl/hemicyanin dyes, and naphthalimide dyes, and mixtures thereof;more preferentially, the fluorescent dyes are direct and cationic; andbetter still, the fluorescent dye(s) (b) are chosen from styryl orhemicyanin cationic dyes.

Better still, the fluorescent dyes of the invention absorb light in theyellow, orange and red range, preferably in the absorption wavelengthλ_(abs) between 400 nm and 500 nm inclusive.

According to one variant, the fluorescent dyes of the invention containat least one cationic radical borne by, or included in, at least one ofthe fluorescent chromophores.

Preferably, the cationic radical is a quaternary ammonium; better still,the cationic charge is endocyclic.

These cationic radicals are, for example, a cationic radical:

-   -   bearing an exocyclic (di/tri)(C₁-C₈)alkylammonium charge, or    -   bearing an endocyclic charge, such as the following cationic        heteroaryl groups: acridinium, benzimidazolium,        benzobistriazolium, benzopyrazolium, benzopyridazinium,        benzoquinolium, benzothiazolium, benzotriazolium, benzoxazolium,        bipyridinium, bis-tetrazolium, dihydrothiazolium,        imidazopyridinium, imidazolium, indolium, isoquinolium,        naphthoimidazolium, naphthoxazolium, naphthopyrazolium,        oxadiazolium, oxazolium, oxazolopyridinium, oxonium,        phenazinium, phenoxazolium, pyrazinium, pyrazolium,        pyrazoyltriazolium, pyridinium, pyridinoimidazolium, pyrrolium,        pyrylium, quinolium, tetrazolium, thiadiazolium, thiazolium,        thiazolopyridinium, thiazoylimidazolium, thiopyrylium,        triazolium or xanthylium.

According to a preferred variant of the invention, the fluorescent dyesof the invention bear at least one cationic chromophore and comprise atleast one quaternary ammonium radical such as polymethine chromophoreschosen from formulae (III) and (IV) below:

W⁺—[C(R^(c))═C(R^(d))]_(m′)—Ar′—(*)Q⁻  (III)

Ar—[C(R^(d))═C(R^(c))]_(m′)—W′⁺—(*)Q⁻  (IV),

in which formulae (III) and (IV):

-   -   W⁺ represents a cationic heteroaryl group, in particular        comprising a quaternary ammonium optionally substituted with one        or more (C₁-C₈)alkyl groups optionally substituted in particular        with one or more hydroxyl groups;    -   W′⁺ represents a divalent heteroaryl radical as defined for W⁺;    -   Ar represents an aryl group such as phenyl or naphthyl,        optionally substituted preferably with i) one or more halogen        atoms such as chlorine or fluorine; ii) one or more (C₁-C₈)alkyl        and preferably C₁-C₄ alkyl groups such as methyl; iii) one or        more hydroxyl groups; iv) one or more (C₁-C₈)alkoxy groups such        as methoxy; v) one or more hydroxy(C₁-C₈)alkyl groups such as        hydroxyethyl, vi) one or more amino or (di)(C₁-C₈)alkylamino        groups, preferably with the C₁-C₄ alkyl part optionally        substituted with one or more hydroxyl groups, such as        (di)hydroxyethylamino, vii) with one or more acylamino        groups; viii) one or more heterocycloalkyl groups such as        piperazinyl, piperidyl or 5- or 6-membered heteroaryl such as        pyrrolidinyl, pyridyl and imidazolinyl;    -   Ar′ is a divalent aryl radical as defined for Ar;    -   m′ represents an integer between 1 and 4 inclusive, in        particular, m′ is 1 or 2; better still 1;    -   R^(c) and R^(d), which may be identical or different, represent        a hydrogen atom or optionally a substituted (C₁-C₈)alkyl and        preferably C₁-C₄ alkyl group, or alternatively R^(c) is        contiguous with W or W′ and/or R^(d) is contiguous with Ar or        Ar′ and form, with the atoms that bear them, a        (hetero)cycloalkyl; in particular, R^(c) is contiguous with W⁺        or W′⁺ and forms a (hetero)cycloalkyl such as cyclohexyl;    -   Q⁻ is an organic or mineral anionic counterion;    -   (*) represents the part of the fluorescent chromophore that is        bonded to the rest of the dye.

Preferably, W⁺ or W′⁺ is an imidazolium, pyridinium, benzimidazolium,pyrazolium, benzothiazolium or quinolinium radical optionallysubstituted with one or more identical or different C₁-C₄ alkylradicals.

According to a particularly preferred embodiment of the invention, thefluorescent chromophore(s) of the dye (III) or (IV) are those definedpreviously with m′=1, Ar representing a phenyl group substituted para tothe styryl group

—C(R^(d))═C(R^(c))— with a (di)(hydroxy)(C₁-C₆)(alkyl)amino group suchas dihydroxy(C₁-C₄)alkylamino, and W′⁺ representing an imidazolium orpyridinium group, preferentially ortho- or para-pyridinium.

According to another preferred variant of the invention, the fluorescentchromophore(s) of the dyes are cationic and comprise at least onequaternary ammonium radical such as a naphthimidyl bearing a cationicexocyclic charge of formula (IIIa) or (IVa):

in which formulae (IIIa) and (IVa) R^(e), R^(f), R^(g) and R^(h), whichmay be identical or different, represent a hydrogen atom or a(C₁-C₆)alkyl group which is optionally substituted, preferentially witha di(C₁-C₆)alkylamino or tri(C₁-C₆)alkylammonium group such astrimethylammonium.

According to a particular embodiment, the fluorescent dye(s) of theinvention (b) are chosen from those of formula (V), (VI) or (VII) below,and also the organic or mineral, acid or base salts thereof, the opticalisomers, geometrical isomers and tautomers thereof, and the solvatesthereof such as hydrates:

in which formulae (V), (VI) and (VII):

-   -   R₁ and R₂, which may be identical or different, represent a        hydrogen atom or a C₁-C₆ alkyl group; preferentially a hydrogen        atom;    -   G₁ represents a hydrogen atom or a group chosen from NH₂ and OH;    -   R_(a), R′_(a), R″_(a), R″′_(a), R_(b), R′_(b), R″_(b) and        R′″_(b), which may be identical or different, represent a) a        hydrogen atom, b) a halogen atom, a group from among: c)        amino, d) (C₁-C₄)alkylamino, e) (C₁-C₄)dialkylamino, f)        cyano, g) carboxyl —C(O)OH or carboxylate —C(O)O⁻, Q⁺, h)        hydroxyl —OH or alkoxide —O⁻Q⁺, i) (poly)halo(C₁-C₆)alkyl such        as trifluoromethyl, j) acylamino, k) (C₁-C₆)alkoxy, 1)        (C₁-C₆)alkylthio, m) (poly)hydroxy(C₂-C₄)alkoxy, n)        (C₁-C₆)alkylcarbonyloxy, o) (C₁-C₆)alkoxycarbonyl, p)        (C₁-C₆)alkylcarbonylamino, q) acylamino, r) carbamoyl, s)        (C₁-C₆)alkylsulfonylamino, t) aminosulfonyl, u) —SO₃H or        sulfonate —SO₃ ⁻, Q⁺ or v) (C₁-C₆)alkyl optionally substituted        with a group chosen from (C₁-C₆)alkoxy, hydroxyl, cyano,        carboxyl, amino, (di)(C₁-C₄)alkylamino, or alternatively the two        alkyl radicals borne by the nitrogen atom of the amino group        form a 5- to 7-membered heterocycle optionally comprising        another nitrogen or non-nitrogen heteroatom; in particular,        R_(a), R′_(a), R″_(a), R″′_(a), R_(b), R′_(b), R″_(b) and        R″′_(b) represent a hydrogen or halogen atom or a (C₁-C₄)alkyl        group, preferably a hydrogen atom;    -   or alternatively two groups R_(a) and R′_(a); R_(b), and R′_(b)        borne by two adjacent carbon atoms together form a benzo or        indeno ring, a fused heterocycloalkyl or fused heteroaryl group;        the benzo, indeno, heterocycloalkyl or heteroaryl ring being        optionally substituted with a halogen atom, an amino,        (C₁-C₄)alkylamino, (C₁-C₄)dialkylamino, nitro, cyano, carboxyl,        hydroxyl or trifluoromethyl group, an acylamino, (C₁-C₄)alkoxy,        (poly)hydroxy(C₁-C₄)alkoxy, (C₁-C₄)alkylcarbonyloxy,        (C₁-C₄)alkoxycarbonyl or (C₁-C₄)alkylcarbonylamino radical, an        acylamino, carbamoyl or alkoxyalkylsulfonylamino radical, an        aminosulfonyl radical, or a (C₁-C₆)alkyl radical optionally        substituted with: a group chosen from (C₁-C₆)alkoxy, hydroxyl,        cyano, carboxyl, amino, (C₁-C₄)alkylamino and        (C₁-C₄)dialkylamino, or alternatively the two alkyl radicals        borne by the nitrogen atom of the amino group form a 5- to        7-membered heterocycle optionally comprising another nitrogen or        non-nitrogen heteroatom; preferentially, R_(a) and R′_(a)        together form a benzo group;    -   or alternatively, two groups R_(i) and R_(a); and/or a group        R′_(i) and R′_(a) together form a fused (hetero)cycloalkyl,        preferentially cycloalkyl such as cyclohexyl;    -   R_(g) represents a hydrogen atom, a (hetero)aryl(C₁-C₄)alkyl        group or a (C₁-C₆)alkyl group that is optionally substituted;        preferentially, R_(b) represents a hydrogen atom or a        (C₁-C₃)alkyl or benzyl group;    -   R_(e) represents a covalent bond, a linear or branched,        optionally substituted (C₁-C₆)alkylene or (C₂-C₈)alkenylene        hydrocarbon-based chain, preferably R_(e) represents an        unsubstituted (C₁-C₆)alkylene;    -   R_(f) represents a hydrogen atom, a (C₁-C₄)alkoxy group, an        amino group R₃R₄N—, a quaternary ammonium group M′, R₃R₄R₅N⁺— in        which R₃, R₄ and R₅, which may be identical or different,        represent a (C₁-C₄)alkyl group or R₃R₄N-represents an optionally        substituted heteroaryl group, preferentially an optionally        substituted imidazolyl group, or alternatively M′, R₃R₄R₅N⁺—        represents an optionally substituted cationic heteroaryl group,        preferentially an imidazolinium group optionally substituted        with a (C₁-C₃)alkyl group;    -   G represents i) a group —NR_(c)R_(d), ii) —OR with R        representing a) a hydrogen atom, b) an optionally substituted,        preferentially unsubstituted (C₁-C₆)alkyl group, c) an        optionally substituted (hetero)aryl group, d) an optionally        substituted (hetero)aryl(C₁-C₆)alkyl group such as benzyl, e)        optionally substituted (hetero)cycloalkyl, f) optionally        substituted (hetero)cycloalkyl(C₁-C₆)alkyl; according to a        particular embodiment, G represents a group —NR_(c)R_(d),        according to another particular embodiment, G represents a        (C₁-C₆)alkoxy group;    -   or alternatively when G represents —NR_(c)R_(d), two groups R,        and R′_(a) and/or R_(d) and R_(a) together form a saturated        heteroaryl or heterocycle, optionally substituted with one or        more (C₁-C₆)alkyl groups, preferentially a 5- to 7-membered        heterocycle containing one or two heteroatoms chosen from        nitrogen and oxygen; more preferentially, the heterocycle is        chosen from morpholinyl, piperazinyl, piperidyl and pyrrolidinyl        groups;    -   R_(c) and R_(d), which may be identical or different, represent        a hydrogen atom or a group from among: a) optionally substituted        (hetero)aryl such as phenyl, b) optionally substituted        (hetero)aryl(C₁-C₄)alkyl, c) optionally substituted        (hetero)cycloalkyl, d) optionally substituted        (hetero)cycloalkyl(C₁-C₄)alkyl, f) (C₂-C₅)alkyl or g)        (C₁-C₈)alkyl which is optionally substituted, preferably        optionally substituted with a hydroxyl, carboxyl, carboxylate,        sulfate or sulfonate group;

or alternatively two adjacent radicals R_(c) and R_(d) borne by the samenitrogen atom together form an optionally substituted heterocyclic oroptionally substituted heteroaryl group;

-   -   R_(i) and R′_(i), which may be identical or different, represent        a hydrogen atom or a (C₁-C₄)alkyl group;

represents a (hetero)aryl group fused to the phenyl ring; oralternatively is absent from the phenyl; preferentially, when the ringis present, the ring is a benzo;

-   -   m represents an integer between 1 and 18 inclusive, particularly        an integer between 1 and 14 inclusive; preferentially an integer        between 2 and 10 inclusive; more preferentially an integer        between 3 and 8; more particularly an integer between 4 and 6;    -   M′ represents an anionic counterion, derived from a salt of an        organic or mineral acid, or from an organic or mineral base that        ensures the electrical neutrality of the dye;    -   Q represents a cationic counterion, derived from a salt of an        organic or mineral acid, or from an organic or mineral base that        ensures the electrical neutrality of the dye such as alkali        metal, alkaline-earth metal or ammonium;        it being understood that when the dye comprises a carboxylate,        sulfonate or alkoxide group, then M′ and Q⁺ may be absent to        ensure the electrical neutrality of said dye.

According to one embodiment, the fluorescent dyes of the invention areof formula (V) as defined previously.

According to a preferred embodiment, the fluorescent dye(s) of theinvention are chosen from the styryl dyes of formula (VIII) below, andalso the organic or mineral, acid or base salts thereof, the opticalisomers, geometrical isomers and tautomers thereof, and the solvatesthereof such as hydrates:

in which formula (VIII) G, G₁, R_(a), R′_(a), R″_(a), R_(b), R′_(b),R″_(b), R_(i), R′_(i), R₁, R₂ and m are as defined previously for (V).

In particular, the dye(s) of the invention are chosen from those offormula (VIII) for which:

-   -   R₁ and R₂, which may be identical or different, represent a        hydrogen atom;    -   R_(i) and R_(i′), which may be identical or different, represent        a hydrogen atom or a (C₁-C₄)alkyl group, preferably hydrogen;    -   R_(a), R′_(a) and R″_(a), which may be identical or different,        represent a hydrogen atom, a halogen atom such as fluorine, or        an —OH, —O⁻Q⁺, (C₁-C₆)alkoxy, nitro, or cyano group, with Q⁺ as        defined previously;    -   R_(b), R′_(b) and R″_(b), which may be identical or different,        represent a hydrogen atom or a (C₁-C₆)alkyl group;    -   or alternatively two contiguous radicals R_(b) and R′_(b) form,        together with the carbon atoms that bear them, a benzo group        that is condensed or fused to the pyridinium group, said benzo        group possibly being substituted; preferably, said benzo group        is unsubstituted;    -   G represents a group —NR_(c)R_(d) or (C₁-C₆)alkoxy group which        is optionally substituted, preferentially unsubstituted;        according to a particular embodiment, G represents a group        —NR_(c)R_(d), according to another particular embodiment, G        represents a (C₁-C₆)alkoxy group;    -   R_(i) and R′_(i), which may be identical or different, represent        a hydrogen atom or a (C₁-C₄)alkyl group;

represents an aryl or heteroaryl group fused to the phenyl ring; oralternatively is absent from the phenyl ring; preferentially, when thering is present, the ring is a benzo;

-   -   m represents an integer between 1 and 18 inclusive; particularly        an integer between 2 and 16 inclusive; preferentially an integer        between 3 and 10; more preferentially an integer between 4 and        6;    -   R_(c) and R_(d), which may be identical or different, represent        a hydrogen atom, a (C₂-C₄)alkyl group or a substituted        (C₁-C₈)alkyl group, preferably (C₂-C₄)alkyl substituted in        particular with one or more groups chosen from i) cyano, ii)        (C₁-C₃)alkoxy, iii) hydroxyl and iv) (C₁-C₃)alkylcarbonyl,        preferably with one or more hydroxyl groups; and    -   M′ representing an anionic counterion, derived from a salt of an        organic or mineral acid, or from an organic or mineral base that        ensures the electrical neutrality of the dye;        it being understood that when the dye comprises an alkoxide        group, then M′ and Q⁺ may be absent to ensure the electrical        neutrality of said dye.

Preferably, the fluorescent dye(s) (b) of the invention are chosen fromthe styryl dyes of formula (IX) below, and also the organic or mineral,acid or base salts thereof, the optical isomers, geometrical isomers andtautomers thereof, and the solvates thereof such as hydrates:

in which formula (IX) G, G₁, R_(a), R′_(a), R_(b), R′_(b) and m are asdefined previously.

According to a particular embodiment, the group G is in the paraposition relative to the —CH═CH— group, i.e. in position 4′ of thephenyl group. According to another particular embodiment of theinvention, the group G is in the ortho position relative to the —CH═CH—group, i.e. in position 2′ of the phenyl group. According to oneembodiment, the —CH═CH— group is in the para position relative to thepyridinium group, i.e. in position 4.

According to another advantageous variant, the —CH═CH— group is in theortho position relative to the pyridinium group, i.e. in position 2.

According to a preferred mode of the invention, the fluorescent dye(s)(b) of the invention are chosen from the compounds of formulae (X) and(XI) below, and also the organic or mineral, acid or base salts thereof,the optical isomers, geometrical isomers and tautomers thereof, and thesolvates thereof such as hydrates:

in which formulae (X) and (XI):

-   -   R¹, R², R³ and R⁴, which may be identical or different,        represent a hydrogen atom or a (C₁-C₆)alkyl group; preferably,        R² and R³ represent a hydrogen atom and R¹ and R⁴, which may be        identical or different, represent a hydrogen atom or a        (C₁-C₄)alkyl group;    -   R⁵, R⁶, R⁷, R⁸ and R⁹, which may be identical or different,        represent i) a hydrogen atom or ii) a halogen atom such as Cl,        Br or F, iii) a group OR in which R represents a hydrogen atom        or Q⁺ as described previously, or a (C₁-C₃)alkyl group, a group        from among iv) aryl such as benzene, v) aryl(C₁-C₃)alkyl such as        benzyl, vi) cyano, vii) nitro, viii) (C₁-C₃)alkylthio, ix) amino        NR⁰R¹¹ with R¹⁰ and R¹¹, which may be identical or different,        representing a) a hydrogen atom, b) a (C₂-C₄)alkyl group or c) a        substituted (C₁-C₅)alkyl group, preferably (C₂-C₄)alkyl group        optionally substituted with one or more groups chosen from:        -   cyano,        -   (C₁-C₃)alkoxy,        -   hydroxyl, and        -   (C₁-C₃)alkylcarbonyl;        -   in particular, R¹⁰ and R¹¹, which may be identical or            different, represent a hydrogen atom or a (C₁-C₆)alkyl group            substituted with one or more hydroxyl, cyano or            (C₁-C₃)alkylcarbonyl groups such as hydroxyethyl;    -   m represents an integer between 1 and 18 inclusive; particularly        an integer between 2 and 16 inclusive; preferentially an integer        between 3 and 10; more preferentially an integer between 4 and        6;    -   M′ represents an anionic counterion as defined previously;        it being understood that when the dye comprises an alkoxide        group, then M′ and Q may be absent to ensure the electrical        neutrality of said dye.

According to a first embodiment of the invention, the fluorescent dye(s)(b) are of formula (X) with:

R¹ R² R³ R⁴ R⁵ R⁶ R⁷ R⁸ R⁹ m H H H H H H H H H 1 H H H H H t-Bu OH t-BuH 5 H H H H H t-Bu OH t-Bu H 5 H H H H H H NH₂ H H 1 H H H H H H NH₂ HOCH₃ 1 H H H H H H OH Br H 5 H H H H H OCH₃ OH OCH₃ H 5 H H H H Cl H OHH Cl 5 H H H H H H OH H H 10 H H H H H OCH₃ OH OCH₃ H 10 H H H H H t-BuOH t-Bu H 10 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 HH H H H H N(CH₂CH₃)₂ H H 1 H H H H H t-Bu OH t-Bu H 10 H H H H H HN(CH₂CH₃)CH₂CH₂OH H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H HN(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H HN(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H1 H H H H H H n-C₆H₁₃ H H 1 H H H H H H N(CH₂CH₂OH)₂ H H 2 H H H H H HN(n-Bu)₂ H H 2 H H H H H OCH₃ OH H H 10 H H H H H H OC₂H₅OH H H 1 H H HH H H OH H H 1 H H benzo H H H H H 1 H H benzo H H N(CH₂CH₂OH)₂ H H 1 HH benzo H H N(CH₂CH₂OH)₂ H H 1and also the organic or mineral, acid or base salts thereof, the opticalisomers, geometrical isomers and tautomers thereof, and the solvatesthereof such as hydrates.

According to a second embodiment, the fluorescent dye(s) (b) are offormula (XI) with:

R¹ R² R³ R⁴ R⁵ R⁶ R⁷ R⁸ R⁹ m CH₃ H H H OH H OCH₃ H H 2 CH₃ H H H H HOCH₃ OCH₂—Ph H 2 CH₃ H H H H H H H OCH₃ 2 CH₃ H H H F H H H H 2 CH₃ H HH H H H OPh H 2 CH₃ H H H H H N(CH₂CH₂OAc)₂ H H 2 CH₃ H H H OCH₃ H OCH₃OCH₃ H 2 CH₃ H H H H H H CH₃ H 2 CH₃ H H H H H OH H H 2 CH₃ H H H H OCH₃OCH₃ OCH₃ H 2 CH₃ H H H H OCH₃ OH OH H 2 CH₃ H H H H H OCH₃ OCH₃ OCH₃ 2CH₃ H H H H H H OCH₃ OH 2 CH₃ H H H H H N(n-butyl)₂ H H 2 CH₃ H H H HOCH₃ OCH₃ H H 2 CH₃ H H H H H H H H 2 CH₃ H H H H H i-propyl H H 2 H H HH H H OH H H 6 H H H H H OCH₃ OCH₃ OCH₃ H 6 H H H H OH H OCH₃ H H 2 H HH H OCH₃ H H OCH₃ OCH₃ 2 H H H H H H H H Br 2 H H H H H H OH H H 2 H H HH OCH₃ OCH₃ OCH₃ H H 6 H H H H OH OCH₃ H H H 6 H H H H H OCH₃ OCH₃ H H 6H H H H H OCH₃ OCH₃ H H 2 H H H H H H C(O)—OH H H 6 H H H H H H C(O)—OHH H 2 H H H H H H i-propyl H H 2 H H H H H H N(CH₃)CH₂CH₂CN H H 2 H H HH H H OCH₃ OCH₂Ph H 2 H H H H H H H OPh H 2 H H H H H HN(CH₂CH₂C(O)CH₃)₂ H H 2 H H H H OH H OCH₃ H H 6 H H H H H OCH₃ OCH₃ OCH₃H 2 H H H H OCH₃ H OCH₃ OCH₃ H 6 H H H H H H H CH₃ H 2 H H H H H HN(CH₃)CH₂CH₂OH H H 2and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates.

Preferably, the fluorescent dye(s) (b) are chosen from those of formulae(X′) and (XI′) below:

in which formulae (X′) and (XI′) R⁵, R⁷, R⁸ and m are as definedpreviously for (X) and (XI), in particular:

-   -   R⁵ and R⁸, which may be identical or different, represent a        hydrogen atom or a (C₁-C₄)alkoxy group such as methoxy;    -   R⁷ represents a (C₁-C₄)alkoxy group or NR¹⁰R¹¹ with R¹⁰        representing a) a hydrogen atom, or b) a (C₁-C₆)alkyl group        optionally substituted with one or more groups chosen from i)        cyano, ii) (C₁-C₃)alkoxy, iii) hydroxyl and iv)        (C₁-C₃)alkylcarbonyl and R¹¹ representing a) a (C₂-C₅)alkyl        group substituted with one or more groups chosen from i)        cyano, ii) (C₁-C₃)alkoxy, iii) hydroxyl and iv)        (C₁-C₃)alkylcarbonyl;    -   in particular, NR¹⁰R¹¹ represents a (C₂-C₄)alkyl group, a        (di)hydroxy(C₂-C₄)alkylamino or        hydroxy(C₂-C₄)alkyl((C₁-C₄)alkyl)amino group;    -   m represents an integer between 1 and 18 inclusive; particularly        an integer between 2 and 16 inclusive; preferentially an integer        between 3 and 10; more preferentially an integer between 4 and        6; and    -   M′ represents an anionic counterion, derived from a salt of an        organic or mineral acid, or from an organic or mineral base that        ensures the electrical neutrality of the dye.

According to this embodiment, the fluorescent dye(s) (b) are preferablychosen from those of formula (X′) or (XI′) with:

R⁵ R⁷ R⁸ m R⁵ R⁷ R⁸ m H N(CH₂CH₂OH)₂ H 2 and OCH₃ OCH₃ OCH₃ 2 HN(CH₂CH₂OH)₂ H 3 OCH₃ OCH₃ OCH₃ 3 H N(CH₂CH₂OH)₂ H 4 OCH₃ OCH₃ OCH₃ 3 HN(CH₂CH₂OH)₂ H 5 OCH₃ OCH₃ OCH₃ 4 H N(CH₂CH₂OH)₂ H 6 OCH₃ OCH₃ OCH₃ 5 HN(CH₂CH₂OH)₂ H 8 OCH₃ OCH₃ OCH₃ 8 H N(CH₂CH₂OH)₂ H 10 OCH₃ OCH₃ OCH₃ 10H N(CH₂CH₂OH)₂ H 12 OCH₃ OCH₃ OCH₃ 12 H N(CH₂CH₂OH)₂ H 14 OCH₃ OCH₃ OCH₃14 H N(CH₂CH₂OH)₂ H 16 OCH₃ OCH₃ OCH₃ 16 H CH₃CH₂N(CH₂CH₂OH) H 2 HCH₃CH₂N(CH₂CH₂OH) H 4and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates.

According to yet another preferred mode of the invention, thefluorescent dye(s) (b) of the invention are chosen from the compounds offormulae (XII) and (XIII) below, and also the organic or mineral, acidor base salts thereof, the optical isomers, geometrical isomers andtautomers thereof, and the solvates thereof such as hydrates:

in which formulae (XII) and (XIII):

-   -   R¹, R², R³ and R⁴, which may be identical or different,        represent a hydrogen atom or a (C₁-C₆)alkyl group; preferably,        R² and R³ represent a hydrogen atom and R¹ and R⁴, which may be        identical or different, represent a hydrogen atom or a        (C₁-C₄)alkyl group;    -   R⁵, R⁶, R⁷, R⁸ and R⁹, which may be identical or different,        represent i) a hydrogen atom or ii) a halogen atom such as Cl,        Br or F, iii) a group OR in which R represents a hydrogen atom        or Q as described previously, or a (C₁-C₃)alkyl group, a group        from among iv) aryl such as benzene, v) aryl(C₁-C₃)alkyl such as        benzyl, vi) cyano, vii) nitro, viii) (C₁-C₃)alkylthio, ix) amino        NR¹⁰R¹¹ with R¹⁰ and R¹¹, which may be identical or different,        representing a) a hydrogen atom or b) a (C₁-C₈)alkyl group        optionally substituted with one or more groups chosen from:        -   cyano,        -   (C₁-C₃)alkoxy,        -   hydroxyl, and        -   (C₁-C₃)alkylcarbonyl;        -   in particular, R¹⁰ and R¹¹, which may be identical or            different, represent a hydrogen atom or a (C₁-C₆)alkyl group            optionally substituted with one or more hydroxyl, cyano or            (C₁-C₃)alkylcarbonyl groups such as methyl, ethyl, butyl,            isobutyl, cyanoethyl, methylcarbonylethyl, or hydroxyethyl;    -   m represents an integer between 1 and 18 inclusive; particularly        an integer between 2 and 16 inclusive; preferentially an integer        between 3 and 10; more preferentially an integer between 4 and        6;    -   M′ represents an anionic counterion derived from salts of        organic or mineral acids preferably originating from Y;        it being understood that when the dye comprises an alkoxide        group, then M′ and Q⁺ may be absent to ensure the electrical        neutrality of said dye.

According to one embodiment of the invention, the fluorescent dye(s) (b)are of formula (XII) with:

R¹ R² R³ R⁴ R⁵ R⁶ R⁷ R⁸ R⁹ m H H H H H H OCH₃ OCH₃ OCH₃ 2 H H H H OHOCH₃ H H H 2 H H H H H H H H H 2 H H H H H OCH₃ OCH₃ H H 2 H H H H OH HOH H H 6 H H H H OCH₃ H OCH₃ OCH₃ H 6 H H H H H H OH H H 6 H H H H OCH₃H H H F 2 H H H H H H C(O)—OH H H 2 H H H H H H Isopropyl H H 2 H H H HH H N(CH₂CH₂C(O)CH₃)₂ H H 2 H H H H OH H OCH₃ H H 2 H H H H H H OH H H 2H H H H H OCH₃ OH OH H 2 H H H H H CH₃ OCH₂Ph CH₃ H 2 H H H H H OCH₃OCH₃ OCH₃ H 2 H H H H H OCH₃ OCH₃ OCH₃ H 6 H H H H H H N(CH₃)₂ H H 6 H HH H H H OCH₃ OCH₃ OCH₃ 6 H H H H H H Phenyl H H 6 H H H H H OCH₃ OCH₃ HH 6 H H H H H H C(O)—OH H H 6 H H H H H H N(n-Butyl)₂ H H 2 H H H H H HOCH₃ OCH₃ H 3 H H H H H H OCH₃ OCH₃ H 2 H H H H H H OCH₃ OCH₃ H 5 H H HH H H OCH₃ H H 3 H H H H H H N(CH₃)₂ H H 3 H H H H H H H H H 3and also the organic or mineral, acid or base salts thereof, the opticalisomers, geometrical isomers and tautomers thereof, and the solvatesthereof such as hydrates.

According to another embodiment, the fluorescent dye(s) (b) are offormula (XIII) with:

R¹ R² R³ R⁴ R⁵ R⁶ R⁷ R⁸ R⁹ m CH₃ H H H OH H OCH₃ H H 2 CH₃ H H H H HOCH₃ OCH₂—Ph H 2 CH₃ H H H H H H H OCH₃ 2 CH₃ H H H F H H H H 2 CH₃ H HH H H H OPh H 2 CH₃ H H H H H N(CH₂CH₂OAc)₂ H H 2 CH₃ H H H OCH₃ H OCH₃OCH₃ H 2 CH₃ H H H H H H CH₃ H 2 CH₃ H H H H H OH H H 2 CH₃ H H H H OCH₃OCH₃ OCH₃ H 2 CH₃ H H H H OCH₃ OH OH H 2 CH₃ H H H H H OCH₃ OCH₃ OCH₃ 2CH₃ H H H H H H OCH₃ OH 2 CH₃ H H H H H N(n-butyl)₂ H H 2 CH₃ H H H HOCH₃ OCH₃ H H 2 CH₃ H H H H H H H H 2 CH₃ H H H H H i-propyl H H 2 H H HH H H OH H H 6 H H H H H OCH₃ OCH₃ OCH₃ H 6 H H H H OH H OCH₃ H H 2 H HH H OCH₃ H H OCH₃ OCH₃ 2 H H H H H H H H Br 2 H H H H H H OH H H 2 H H HH H H N(CH₃)₂ H H 6 H H H H OCH₃ OCH₃ OCH₃ H H 6 H H H H OH OCH₃ H H H 6H H H H H OCH₃ OCH₃ H H 6 H H H H H OCH₃ OCH₃ H H 2 H H H H H H C(O)—OHH H 6 H H H H H H C(O)—OH H H 2 H H H H H H i-propyl H H 2 H H H H H HN(CH₃)CH₂CH₂CN H H 2 H H H H H H OCH₃ OCH₂Ph H 2 H H H H H H H OPh H 2 HH H H H H N(CH₂CH₂C(O)CH₃)₂ H H 2 H H H H OH H OCH₃ H H 6 H H H H H OCH₃OCH₃ OCH₃ H 2 H H H H OCH₃ H OCH₃ OCH₃ H 6 H H H H H H H CH₃ H 2 H H H HH H N(CH₃)CH₂CH₂OH H H 2 CH₃ H H H H H N(CH₃)₂ H H 2and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates.

More particularly, the fluorescent dyes (b) of the invention are chosenfrom those of formulae (XII′) and (XIII′) below:

in which formulae (XII′) and (XIII′) R⁵, R⁷, R⁸ and m are as definedpreviously for (X) and (XI), in particular:

-   -   R⁵ and R⁸, which may be identical or different, represent a        hydrogen atom or a (C₁-C₄)alkoxy group such as methoxy;    -   R⁷ represents a (C₁-C₄)alkoxy group or NR¹⁰R¹¹ with R¹⁰ and R¹¹,        which may be identical or different, representing a) a hydrogen        atom, or b) a (C₁-C₈)alkyl group optionally substituted with one        or more groups chosen from i) cyano, ii) (C₁-C₃)alkoxy, iii)        hydroxyl, and iv) (C₁-C₃)alkylcarbonyl; in particular, R¹⁰ and        R¹¹, which may be identical or different, represent a hydrogen        atom or a (C₁-C₆)alkyl group optionally substituted with one or        more groups from the following: hydroxyl, cyano or        (C₁-C₃)alkylcarbonyl such as methyl, ethyl, butyl, isobutyl,        cyanoethyl, methylcarbonylethyl or hydroxyethyl; preferably, R¹⁰        and R¹¹, which may be identical or different, represent a        (C₁-C₆)alkyl group optionally substituted with one or more        hydroxyl groups such as hydroxyethyl;    -   m represents an integer between 1 and 18 inclusive; particularly        an integer between 2 and 16 inclusive; preferentially an integer        between 3 and 10; more preferentially an integer between 4 and        6; and    -   M′ represents an anionic counterion, derived from a salt of an        organic or mineral acid, or from an organic or mineral base that        ensures the electrical neutrality of the dye.

According to one embodiment, the fluorescent dye(s) (b) of the inventionare of formula (XII′) or (XIII′) with:

R⁵ R⁷ R⁸ m R⁵ R⁷ R⁸ m H N(CH₂CH₂OH)₂ H 2 and OCH₃ OCH₃ OCH₃ 2 HN(CH₂CH₂OH)₂ H 3 OCH₃ OCH₃ OCH₃ 3 H N(CH₂CH₂OH)₂ H 4 OCH₃ OCH₃ OCH₃ 3 HN(CH₂CH₂OH)₂ H 5 OCH₃ OCH₃ OCH₃ 4 H N(CH₂CH₂OH)₂ H 6 OCH₃ OCH₃ OCH₃ 5 HN(CH₂CH₂OH)₂ H 8 OCH₃ OCH₃ OCH₃ 8 H N(CH₂CH₂OH)₂ H 10 OCH₃ OCH₃ OCH₃ 10H N(CH₂CH₂OH)₂ H 12 OCH₃ OCH₃ OCH₃ 12 H N(CH₂CH₂OH)₂ H 14 OCH₃ OCH₃ OCH₃14 H N(CH₂CH₂OH)₂ H 16 OCH₃ OCH₃ OCH₃ 16and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates.

More particularly, the fluorescent dye(s) (b) of the invention arechosen from those of formula (V), (VIII) or (IX) as defined previouslyin which G represents a hydrogen atom.

More particularly, the fluorescent dye(s) (b) of the invention arechosen from those of formulae (XIV) and (XV) below:

in which formulae (XIV) and (XV) R⁵, R⁷, R⁸ and m are as definedpreviously for (X) and (XI), in particular:

-   -   R⁵ and R⁸, which may be identical or different, represent a        hydrogen atom or a (C₁-C₄)alkoxy group such as methoxy,        preferably, R⁵ and R⁸ represent a hydrogen atom;    -   R⁷ represents a (C₁-C₄)alkoxy group or NR¹⁰R¹¹ with R¹⁰ and R¹¹,        which may be identical or different, representing a) a hydrogen        atom, or b) a (C₁-C₈)alkyl group optionally substituted with one        or more groups chosen from i) hydroxyl, ii) R—Z—C(X)—Y— with X,        Y and Z representing an oxygen or sulfur atom or N(R′), or        alternatively X and/or Z represent a bond, R and R′, which may        be identical or different, represent a hydrogen atom or a        (C₁-C₆)alkyl group, preferably, X represents an oxygen        atom, iii) sulfonic SO₃H, iv) sulfonate SO₃ ⁻, Q⁺, v)        carboxylate C(O)O⁻, Q⁺ with Q⁺ representing a cationic        counterion such as an alkali metal or alkaline-earth metal; in        particular, R⁷ represents a group NR¹⁰R¹¹ with R¹⁰ and R¹¹,        which may be identical or different, representing a) a hydrogen        atom, or b) a (C₁-C₆)alkyl group optionally substituted with one        or more groups chosen from i) hydroxyl, ii) carboxyl, iii)        carboxylate, iv) sulfonic, and v) sulfonate, more particularly        chosen from identical or different groups representing a) a        hydrogen atom, or b) a (C₁-C₆)alkyl group optionally substituted        with one or more groups chosen from i) hydroxyl, ii) carboxyl,        and iii) carboxylate;    -   m represents an integer between 1 and 18 inclusive; particularly        an integer between 1 and 6 inclusive; preferentially an integer        between 1 and 4; more preferentially an integer between 1 and 2;        and    -   M′ represents an anionic counterion, derived from a salt of an        organic or mineral acid, or from an organic or mineral base that        ensures the electrical neutrality of the dye;        it being understood that when the dye comprises a sulfonate or        carboxylate group, then M′ and Q may be absent to ensure the        electrical neutrality of said dye.

More preferentially, the fluorescent dye(s) (b) of the invention arechosen from the following compounds, and also the geometrical isomersthereof, the tautomers thereof, the solvates thereof and mixturesthereof:

with M′ and Q⁺ as defined previously.

The Oxidizing Agents

The process for dyeing keratin fibres and the cosmetic compositionaccording to the present invention may also optionally use, or comprise,one or more oxidizing agents.

Preferably, the oxidizing agent(s) are chosen from chemical oxidizingagents.

The term “chemical oxidizing agent” means an oxidizing agent other thanatmospheric oxygen.

More particularly, the chemical oxidizing agent(s) are chosen fromhydrogen peroxide, hydrogen peroxide-generating systems, urea peroxide,alkali metal bromates or ferricyanides, peroxygenated salts, forinstance persulfates, perborates, peracids and precursors thereof andpercarbonates of alkali metals or alkaline-earth metals, and mixturesthereof.

Preferably, the chemical oxidizing agent(s) are chosen from hydrogenperoxide and hydrogen peroxide-generating systems.

According to a preferred embodiment, the hydrogen peroxide-generatingsystem(s) are chosen from urea peroxide; polymeric complexes that canrelease hydrogen peroxide, chosen from polyvinylpyrrolidone/H₂O₂;oxidases; perborates; and percarbonates.

Preferably, the chemical oxidizing agent is hydrogen peroxide, and morepreferentially aqueous hydrogen peroxide solution.

The chemical oxidizing agent(s) are advantageously applied in the formof an aqueous solution of which the content of chemical oxidizing agentsis preferably between 0.05% and 5% by weight and more preferentiallybetween 0.1% and 2% by weight, relative to the total weight of theaqueous solution.

According to a preferred embodiment of the invention, the dyeing processdoes not use any oxidizing agent.

According to this preferred embodiment of the invention, the cosmeticcomposition comprising ingredients (a) and (b) does not comprise anyoxidizing agent.

The Reducing Agents

The process for dyeing keratin fibres and the cosmetic compositionaccording to the present invention may also optionally use, or comprise,one or more reducing agents.

The reducing agent(s) that are useful in the present invention areadvantageously chosen from the compounds of formula (XVI) below, andalso the addition salts thereof and mixtures thereof:

H(X)_(q)(R₁₀)_(t)  (XVI)

in which formula (XVI):

-   -   X represents P, S or SO₂,    -   q represents an integer equal to 0 or 1,    -   t represents an integer equal to 1 or 2, and    -   R represents a linear or branched, saturated or unsaturated C₁        to C₂₀ alkyl radical, optionally interrupted with a heteroatom,        and/or optionally substituted with one or more radicals chosen        from hydroxyl, halo, amine, carboxyl, ((C₁-C₃₀)alkoxy)carbonyl,        amido, ((C₁-C₃₀)alkyl)aminocarbonyl, ((C₁-C₃₀)acyl)amino, mono-        or dialkylamino, and mono- or dihydroxylamino radicals.

Preferably, the reducing agent(s) are chosen from thioglycolic acid,thiolactic acid, glyceryl monothioglycolate, cysteamine,N-acetylcysteamine, N-propionylcysteamine, cysteine, N-acetylcysteine,thiomalic acid, pantetheine, 2,3-dimercaptosuccinic acid,N-(mercaptoalkyl)-ω-hydroxyalkylamides, N-mono- orN,N-dialkylmercapto-4-butyramides, aminomercaptoalkylamides,N-(mercaptoalkyl)succinamic acid and N-(mercaptoalkyl)succinimidederivatives, alkylamino mercaptoalkylamides, the azeotropic mixture of2-hydroxypropyl thioglyconate and of (2-hydroxy-1-methyl)ethylthioglycolate, mercaptoalkylaminoamides, N-mercaptoalkylalkanediamidesand formamidinesulfinic acid derivatives, salts thereof, and mixturesthereof.

Preferably, the reducing agent(s) are also chosen from salts such assodium sulfite, sodium dithionite or sodium thiosulfate, and mixturesthereof.

The chemical reducing agent(s) are advantageously applied in the form ofan aqueous solution of which the content of chemical reducing agents ispreferably between 0.01% and 10% by weight and more preferentiallybetween 0.1% and 5% by weight, relative to the total weight of theaqueous solution.

According to a preferred embodiment of the invention, the dyeing processdoes not use any reducing agent.

According to this preferred embodiment of the invention, the cosmeticcomposition comprising ingredients (a) and (b) does not comprise anyreducing agent.

The Cosmetic Medium and the Solvents

The 2- or 4-azopyridinium dye(s) (a) chosen from the compounds offormula (I) or (II), as defined previously, and (b) the fluorescentdye(s), as defined previously, and also, when they are present, theoxidizing agent(s) and/or the reducing agent(s), may be dissolvedbeforehand before being applied to the keratin fibres.

In other words, the ingredients used in the dyeing process of thepresent invention may be present in one or more compositions.

The composition(s) comprising the ingredients according to the presentinvention are cosmetic compositions, i.e. they are preferably aqueous.Besides water, they may comprise one or more organic solvents, ormixtures thereof.

Examples of organic solvents that may be mentioned include linear orbranched C₂ to C₄ alkanols, such as ethanol and isopropanol; glycerol;polyols and polyol ethers, for instance 2-butoxyethanol, propyleneglycol, hexylene glycol, dipropylene glycol, propylene glycol monomethylether, diethylene glycol monomethyl ether and monoethyl ether, and alsoaromatic alcohols or ethers, for instance benzyl alcohol orphenoxyethanol, and mixtures thereof.

The pH

The pH of the composition(s) used in the dyeing process of the inventionand of the composition of the invention comprising ingredients (a) and(b) is preferably between 2 and 12 and more preferentially between 3 and11. It may be adjusted to the desired value by means of acidifying orbasifying agents usually used in the dyeing of keratin fibres, oralternatively using standard buffer systems.

The pH of the composition which comprises ingredients (a) and (b) andthat of the composition(s) used in the dyeing process of the inventionis preferably between 6 and 11 inclusive, more preferentially between 7and 10 and better still between 7.5 and 9.5, such as between 9 and 9.5.

Among the acidifying agents as defined previously, mention may be made,by way of example, of mineral or organic acids, for instancehydrochloric acid, orthophosphoric acid or sulfuric acid, carboxylicacids, for instance acetic acid, tartaric acid, citric acid and lacticacid, and sulfonic acids.

The alkaline agent(s) may be chosen especially from mineral, organic orhybrid alkaline agents, and mixtures thereof.

The mineral alkaline agent(s) are preferably chosen from aqueousammonia, alkaline carbonates or bicarbonates such as ammonium, sodium orpotassium carbonate or bicarbonate, ammonium, sodium or potassiumhydroxide, or mixtures thereof.

The organic alkaline agent(s) are preferably chosen from organic amineswith a pK_(b) at 25° C. of less than 12, preferably of less than 10 andmore advantageously still of less than 6. It should be noted that itconcerns the pK_(b) corresponding to the function having the highestbasicity. In addition, the organic amines do not comprise any alkyl oralkenyl fatty chain comprising more than ten carbon atoms.

The organic alkaline agent(s) are preferably chosen from alkanolamines,in particular mono-, di- or trihydroxy(C₁-C₆)alkylamines, such astriethanolamine, oxyethylenated and/or oxypropylenated ethylenediamines,amino acids, polyamines of formula (XVII) below, and mixtures thereof:

in which formula (XVII) W is a divalent C₁ to C₆ alkylene radicaloptionally substituted with one or more hydroxyl groups or a C₁ to C₆alkyl radical, and/or optionally interrupted with one or moreheteroatoms such as O, or NR_(u); R_(x), R_(y), R_(z), R_(t) and R_(u),which may be identical or different, represent a hydrogen atom or a C₁to C₆ alkyl, C₁ to C₆ hydroxyalkyl or C₁ to C₆ aminoalkyl radical.

Examples of amines of formula (XVII) that may be mentioned include1,3-diaminopropane, 1,3-diamino-2-propanol, spermine and spermidine.

The term “alkanolamine” means an organic amine comprising a primary,secondary or tertiary amine function, and one or more linear or branchedC₁ to C₈ alkyl groups bearing one or more hydroxyl radicals.

Organic amines chosen from alkanolamines such as monoalkanolamines,dialkanolamines or trialkanolamines comprising one to three identical ordifferent C₁ to C₄ hydroxyalkyl radicals are in particular suitable foruse in the invention.

Among the compounds of this type, mention may be made ofmonoethanolamine (MEA), diethanolamine, triethanolamine,monoisopropanolamine, diisopropanolamine, N,N-dimethylethanolamine,2-amino-2-methyl-1-propanol, triisopropanolamine,2-amino-2-methyl-1,3-propanediol, 3-amino-1,2-propanedio1,3-dimethylamino-1,2-propanediol and tris(hydroxymethyl)aminomethane.

More particularly, the amino acids that may be used are of natural orsynthetic origin, in their L, D or racemic form, and comprise at leastone acid function chosen more particularly from carboxylic acid,sulfonic acid, phosphonic acid and phosphoric acid functions. The aminoacids may be in neutral or ionic form.

As amino acids that may be used in the present invention, mention may bemade in particular of aspartic acid, glutamic acid, alanine, arginine,ornithine, citrulline, asparagine, carnitine, cysteine, glutamine,glycine, histidine, lysine, isoleucine, leucine, methionine,N-phenylalanine, proline, serine, taurine, threonine, tryptophan,tyrosine and valine.

Advantageously, the amino acids are basic amino acids comprising anadditional amine function optionally included in a ring or in a ureidofunction.

Such basic amino acids are preferably chosen from those corresponding toformula (XVIII) below, and also salts thereof:

R—CH₂—CH(NH₂)—C(O)—OH  (XVIII)

in which formula (XVIII) R represents a group chosen from imidazolyl,preferably imidazolyl-4-yl; aminopropyl; aminoethyl;—(CH₂)₂N(H)—C(O)—NH₂; and —(CH₂)₂—N(H)—C(NH)—NH₂.

The compounds corresponding to formula (XVIII) are histidine, lysine,arginine, ornithine and citrulline.

The organic amine may also be chosen from organic amines of heterocyclictype. Besides histidine that has already been mentioned in the aminoacids, mention may in particular be made of pyridine, piperidine,imidazole, triazole, tetrazole and benzimidazole.

The organic amine may also be chosen from amino acid dipeptides. Asamino acid dipeptides that may be used in the present invention, mentionmay be made especially of carnosine, anserine and balenine.

The organic amine may also be chosen from compounds comprising aguanidine function. As amines of this type that may be used in thepresent invention, besides arginine, which has already been mentioned asan amino acid, mention may be made in particular of creatine,creatinine, 1,1-dimethylguanidine, 1,1-diethylguanidine, glycocyamine,metformin, agmatine, n-amidinoalanine, 3-guanidinopropionic acid,4-guanidinobutyric acid and2-([amino(imino)methyl]amino)ethane-1-sulfonic acid.

Hybrid compounds that may be mentioned include the salts of the aminesmentioned previously with acids such as carbonic acid or hydrochloricacid.

Guanidine carbonate or monoethanolamine hydrochloride may be used inparticular.

Preferably, the alkaline agent(s) that are useful in the invention arechosen from aqueous ammonia, alkaline carbonates or bicarbonates,alkanolamines, amino acids in neutral or ionic form, in particular basicamino acids, and preferably corresponding to those of formula (XVIII).

More preferentially, the alkaline agent(s) are chosen from aqueousammonia, ammonium bicarbonate, ammonium hydroxide, mono-, di- ortrihydroxy(C₁-C₆)alkylamines, such as triethanolamine, and mixturesthereof.

Forms of the Composition

The composition(s) comprising the 2- or 4-azopyridinium dye(s) (a)chosen from the compounds of formula (I) or (II) as defined previously,and the fluorescent dye(s) (b) as defined previously, may be in variouspresentation forms, such as in the form of liquids, lotions, creams orgels or in any other form that is suitable for dyeing keratin fibres.

It may also be packaged under pressure in an aerosol can in the presenceof a propellant or in a non-aerosol can and may form a foam.

Additives

When the ingredients used in the dyeing process according to the presentinvention are present in one or more composition(s), said compositionsmay also optionally comprise one or more additives, different from theingredients of the invention and among which mention may be made offatty substances, cationic, anionic, nonionic, amphoteric orzwitterionic surfactants, cationic, anionic, nonionic or amphotericpolymers or mixtures thereof, antidandruff agents, anti-seborrhoeaagents, agents for preventing hair loss and/or for promoting hairregrowth, vitamins and provitamins including panthenol, sunscreens,mineral or organic pigments, sequestrants, plasticizers, solubilizers,acidifying agents, mineral or organic thickeners, especially polymericthickeners, opacifiers or nacreous agents, antioxidants, hydroxy acids,fragrances, preserving agents, pigments and ceramides.

Needless to say, a person skilled in the art will take care to selectthis or these optional additional compound(s) such that the advantageousproperties intrinsically associated with the composition(s) inaccordance with the invention are not, or are not substantially,adversely affected by the envisaged addition(s).

The above additives may generally be present in an amount, for each ofthem, of between 0 and 20% by weight relative to the total weight of thecomposition comprising them.

The Dyeing Process

The process for dyeing keratin fibres according to the present inventioncomprises the application to said keratin fibres of the followingingredients: (a) one or more 2- or 4-azopyridinium dyes chosen from thecompounds of formula (I) or (II) as defined previously, and also theoptical isomers thereof, the geometrical isomers thereof, the tautomersthereof, the organic or mineral, acid or base salts thereof, thesolvates thereof such as hydrates, and mixtures thereof, and (b) one ormore fluorescent dyes, as defined previously,

it being understood that the 2- or 4-azopyridinium dye(s) (a)(ingredients (a)) and the fluorescent dye(s) (ingredients (b)) areapplied to said keratin fibres together or sequentially.

In other words, the dyeing process according to the present inventionmay be performed in one or more steps.

According to a particularly preferred embodiment, the 2- or4-azopyridinium dye(s) (a) and the fluorescent dye(s) (b), as definedpreviously, are applied together (or jointly), i.e. simultaneously, tothe keratin fibres. According to this embodiment, the dyeing process isperformed in one step.

According to this one-step embodiment, the process comprises a step ofapplying to said keratin fibres a cosmetic composition according to theinvention which comprises one or more 2- or 4-azopyridinium dyes (a)chosen from the compounds of formula (I) or (II) as defined previously,and also the optical isomers thereof, the geometrical isomers thereof,the tautomers thereof, the organic or mineral, acid or base saltsthereof, the solvates thereof such as hydrates, and mixtures thereof,and one or more fluorescent dyes (b) as defined previously.

According to another particularly preferred embodiment, the 2- or4-azopyridinium dye(s) (a), as defined previously, and the fluorescentdye(s) (b), as defined previously, are applied sequentially, i.e.successively. According to this other embodiment, the dyeing process isperformed in at least two steps.

According to a first embodiment in at least two steps, the fluorescentdye(s) (b), as defined previously, are applied to the keratin fibressubsequently to the 2- or 4-azopyridinium dye(s) (a), as definedpreviously. In other words, the fluorescent dye(s) (b), as definedpreviously, are applied after the 2- or 4-azopyridinium dye(s) (a), asdefined previously.

According to this first embodiment, the process for dyeing keratinfibres comprises at least the following two successive steps:

-   -   a first step of applying to said keratin fibres a cosmetic        composition comprising one or more 2- or 4-azopyridinium        dyes (a) chosen from the compounds of formula (I) or (II) as        defined previously, and also the optical isomers thereof, the        geometrical isomers thereof, the tautomers thereof, the organic        or mineral, acid or base salts thereof, the solvates thereof        such as hydrates, and mixtures thereof, followed by    -   a second step of applying to said keratin fibres a cosmetic        composition which comprises one or more fluorescent dyes (b), as        defined previously.

According to a preferred embodiment in at least two steps, the 2- or4-azopyridinium dye(s) (a), as defined previously, are applied to thekeratin fibres subsequently to the fluorescent dye(s) (b), as definedpreviously. In other words, the 2- or 4-azopyridinium dye(s) (a), asdefined previously, are applied after the fluorescent dye(s) (b), asdefined previously.

According to this preferred embodiment, the process for dyeing keratinfibres comprises at least the following two successive steps:

-   -   a first step of applying to said keratin fibres a cosmetic        composition comprising one or more fluorescent dyes (b), as        defined previously, followed by    -   a second step of applying to said keratin fibres a cosmetic        composition comprising one or more 2- or 4-azopyridinium        dyes (a) chosen from the compounds of formula (I) or (II) as        defined previously, and also the optical isomers thereof, the        geometrical isomers thereof, the tautomers thereof, the organic        or mineral, acid or base salts thereof, the solvates thereof        such as hydrates, and mixtures thereof.

Preferably, ingredients (a) and (b) are applied to the keratin fibres ina bath ratio that may range from 0.1 to 10 and more particularly from0.2 to 8. For the purposes of the present invention, the term “bathratio” means the ratio between the total weight of ingredient (a) or (b)and the total weight of keratin fibres to be treated.

When the dyeing process is performed in one step, ingredients (a) and(b) are advantageously left to stand on the keratin fibres for a timeranging from 1 to 90 minutes and more preferentially for a time rangingfrom 5 to 60 minutes.

When the dyeing process is performed in at least two steps, each of theingredients (a) and (b) may be advantageously left to stand on thekeratin fibres for a time ranging from 1 to 60 minutes and morepreferentially for a time ranging from 5 to 50 minutes.

On conclusion of the dyeing process according to the invention, in oneor at least two steps, the keratin fibres are advantageously rinsed withwater. They may optionally be washed with a shampoo, followed by rinsingwith water, before being dried or left to dry.

When the dyeing process is performed in at least two steps, the keratinfibres are advantageously rinsed with water between each step. In otherwords, the dyeing process may comprise an intermediate rinsing stepbetween the application of the first ingredient and the application ofthe second ingredient. During this intermediate rinsing step, thekeratin fibres may optionally be washed with a shampoo, followed byrinsing with water, before being dried or left to dry.

The dyeing process according to the present invention may be performedat room temperature (25° C.) or with heating.

When they are present, the reducing agent(s) may be applied separatelyor together with one of the ingredients (a) or (b). Preferably, whenthey are present, the reducing agent(s) are applied together with theingredient (b).

When they are present, the oxidizing agent(s) may be applied separatelyor together with one of the ingredients (a) or (b). Preferably, whenthey are present, the oxidizing agent(s) are applied after theingredients (a) and (b).

According to a particular embodiment, the process for dyeing keratinfibres according to the present invention comprises the followingsuccessive steps:

-   -   a first step of applying to said keratin fibres a cosmetic        composition comprising one or more 2- or 4-azopyridinium        dyes (a) chosen from the compounds of formula (I) or (II) as        defined previously, and also the optical isomers thereof, the        geometrical isomers thereof, the tautomers thereof, the organic        or mineral, acid or base salts thereof, the solvates thereof        such as hydrates, and mixtures thereof, followed by    -   a second step of applying to said keratin fibres a cosmetic        composition comprising one or more fluorescent dyes (b), as        defined previously, and one or more reducing agents, as defined        previously.

According to a particular embodiment of the dyeing process of theinvention, no step of said process involves an oxidizing agent.

According to another advantageous embodiment of the dyeing process ofthe invention, no step of said process involves a reducing agent.

The dyeing process according to the present invention may be applied towet or dry, preferably dry, keratin fibres.

The Multi-Compartment Device

The present invention also relates to a multi-compartment devicecomprising a first compartment containing one or more 2- or4-azopyridinium dyes (a) chosen from the compounds of formula (I) or(II) as defined previously, and also the optical isomers thereof, thegeometrical isomers thereof, the tautomers thereof, the organic ormineral, acid or base salts thereof, the solvates thereof such ashydrates, and mixtures thereof, and a second compartment containing oneor more fluorescent dyes (b) as defined previously.

Use

A subject of the present invention is also the use of one or morefluorescent dyes (b), as defined previously, combined with one or more2- or 4-azopyridinium dyes (a) chosen from the compounds of formula (I)or (II), as defined previously, and also the optical isomers thereof,the geometrical isomers thereof, the tautomers thereof, the organic ormineral, acid or base salts thereof, the solvates thereof such ashydrates, and mixtures thereof, for the dyeing of light keratin fibres,especially human keratin fibres such as the hair, in chestnut-brown,dark chestnut-brown, brown, brown with a glint or even black, withoutusing an additional dye other than (a) or (b).

According to a particular embodiment, the “keratin fibres” are humankeratin fibres and more particularly the hair.

The examples that follow serve to illustrate the invention without,however, being limiting in nature.

EXAMPLES

In the examples that follow, all the amounts are given as weightpercentages relative to the total weight of the composition, unlessotherwise indicated.

I. Example 1: Sequential Application of 4-Azopyridinium Dye of Formula(I) Followed by Fluorescent Dye a) Preparation of the Compositions

Compositions (A1) and (A2), comprising a 4-azopyridinium dye of formula(I) according to the invention, were prepared from the ingredients whosecontents are mentioned in the table below.

Composition A1 Composition A2

5 × 10⁻³ mol —

— 5 × 10⁻³ mol Aqueous ammonia pH = 9-9.5 pH = 9-9.5 Water qs 100 qs 100Colour in solution Dark blue Dark blue

Composition (B), comprising a fluorescent dye, was prepared from theingredients whose contents are indicated in the table below.

Compo- sition B

5 × 10⁻³ mol Aqueous ammonia pH = 9-9.5 Water qs 100 Colour in solutionRed-orange

b) Procedure

Compositions (A1) and (A2) obtained above were applied to 0.5 g locks ofhair containing 90% white hairs, in a bath ratio equal to 2.

After a leave-on time of 30 minutes at room temperature, the locks ofhair were rinsed with water, washed with shampoo and dried under a hoodfor 5 minutes.

Composition (B), obtained above, was then applied to each of the locksof hair, in a bath ratio equal to 2.

After a leave-on time of 20 minutes at room temperature, the locks ofhair were rinsed with water, washed with shampoo and dried under a hoodfor 5 minutes.

The colour of the locks was evaluated visually.

c) Results

The results of the colouring on the locks of hair containing 90% whitehairs are given in the table below.

Locks dyed with Locks dyed with A1 + B A2 + B Colour after dyeing Blackwithh a bluish Black with a violet glint glint

The results obtained above show that the sequential application of a4-azopyridinium dye of formula (I) according to the present inventionand of a fluorescent dye makes it possible to obtain very intense andchromatic colours.

These results also show that the process according to the invention,using only two particular direct dyes, a 4-azopyridinium dye of formula(I) combined with a fluorescent dye, makes it possible to obtain blackcolours.

II. Example 2: Sequential Application of Fluorescent Dye Followed by4-Azopyridinium Dye of Formula (I) a) Preparation of the Compositions

Compositions (A1), (A2) and (B) were prepared from the ingredientsmentioned in Example 1.

b) Procedure

Composition (B) obtained above was applied to 0.5 g locks of haircontaining 90% white hairs, in a bath ratio equal to 2.

After a leave-on time of 20 minutes at room temperature, the locks ofhair were rinsed with water, washed with shampoo and dried under a hoodfor 5 minutes.

Next, each of the compositions (A1) and (A2), obtained above, was thenapplied to each of the locks of hair, in a bath ratio equal to 2.

After a leave-on time of 30 minutes at room temperature, the locks ofhair were rinsed with water, washed with shampoo and dried under a hoodfor 5 minutes.

The colour of the locks was evaluated visually.

c) Results

The results of the colouring on the locks of hair containing 90% whitehairs are given in the table below.

Locks dyed with Locks dyed with B + A1 B + A2 Colour after Black with abluish Black with a violet dyeing glint glint

The results obtained above show that the sequential application of afluorescent dye and of a 4-azopyridinium dye of formula (I) according tothe present invention makes it possible to obtain very intense andchromatic colours.

These results also show that the process according to the invention,using only two particular direct dyes, a 4-azopyridinium dye of formula(I) combined with a fluorescent dye, makes it possible to obtain blackcolours.

III. Example of Combined Application a) Compositions

Compositions (C1) to (C4) were prepared from the ingredients whosecontents are indicated in the table below.

C1 C2 C3 C4

5 × 10⁻³ mol — — —

— 5 × 10⁻³ mol — —

— — 5 × 10⁻³ mol —

— — — 5 × 10⁻³ mol

5 × 10⁻³ mol — — —

— 5 × 10⁻³ mol 5 × 10⁻³ mol 5 × 10⁻³ mol Aqueous ammonia pH = 9-9.5 pH =9-9.5 pH = 9-9.5 pH = 9-9.5 Water qs 100 qs 100 qs 100 qs 100

b) Procedure

Each of the compositions (C1) to (C4) obtained above was applied to 0.5g locks of hair containing 90% white hairs, in a bath ratio equal to 2.

After a leave-on time of 45 minutes at room temperature, the locks ofhair were rinsed with water, washed with shampoo and dried under a hoodfor 5 minutes.

The colour of the locks was evaluated visually.

c) Results

The results of the colouring on the locks of hair containing 90% whitehairs are given in the table below.

C1 C2 C3 C4 Colour after dyeing Black Black Orange- Black with a brownwith a bluish violet glint glint

The results obtained above show that the process according to theinvention makes it possible to obtain very intense and chromaticcolours.

These results also show that the combination of only two particulardirect dyes, i.e. a 4-azopyridinium dye of formula (I) combined with afluorescent dye, makes it possible to obtain brown or black colours.

1. Process for dyeing keratin fibres, in particular human keratin fibressuch as the hair, comprising the application to said keratin fibres ofthe following ingredients: (a) one or more 2- or 4-azopyridinium dyeschosen from the compounds of formula (I) or (II) below, the opticalisomers thereof, the geometrical isomers thereof, the tautomers thereof,the organic or mineral, acid or base salts thereof, the solvates thereofsuch as hydrates, and mixtures thereof,

in which formulae (I) and (II): R₁ and R′₁, which may be identical ordifferent, represent an optionally substituted linear or branched C₁ toC₆ alkyl radical; R₂ and R′₂, which may be identical or different,represent: a halogen atom, preferentially a chlorine atom, or a linearor branched C₁ to C₄ alkyl radical; R₃ and R′₃, which may be identicalor different, represent, independently of each other: a C₁ to C₄ alkylradical, preferably methyl or ethyl, a (di)(C₁-C₄)(alkyl)amino radical,a (C₁-C₄)alkylcarbonylamino radical, preferably acylamino (—NHCOCH₃), ahydroxyl radical, a halogen atom, preferably a chlorine atom, a C₁ to C₄alkoxy radical, preferably methoxy or ethoxy, a (C₁-C₄)alkylthioradical, or alternatively, two adjacent radicals R₃ or R′₃ together forma 6-membered aromatic ring optionally substituted with one or morehydroxyl or amino groups; R₄ and R′₄, which may be identical ordifferent, represent: a (di)(C₁-C₄)(alkyl)amino radical, a hydroxylradical, a C₁ to C₄ alkoxy radical, preferably methoxy or ethoxy, aradical —NR₅R₆, in which R₅ and R₆, which may be identical or different,represent, independently of each other: a linear or branched, optionallysubstituted C₁ to C₂₀ alkyl radical, or a phenyl radical, oralternatively, two radicals R₃ of formula (I) or R′₃ of formula (II)located, respectively, ortho to the group R₄ (formula (I)) or R′₄(formula (II)) form, respectively, with R₅ and R₆ of the group R₄(formula (I)) or of the group R′₄ (formula (II)) a 6- to 10-memberedheterocycle optionally comprising one or more heteroatoms, preferablythe phenyl group substituted with R₃ and R₄ or R′₃ and R′₄ represents ajulolidine group; m, m′, n and n′ are integers ranging from 0 to 4; Yrepresents an anionic counterion or a mixture of organic or inorganicanions which ensure the electrical neutrality of the compounds offormula (I) and/or (II); and (b) one or more fluorescent dyes; it beingunderstood that the 2- or 4-azopyridinium dye(s) (a) and the fluorescentdye(s) (b) are applied to said keratin fibres together or sequentially.2. Process according to claim 1, characterized in that R₁ and R′₁, whichmay be identical or different, represent a linear C₁ to C₆ alkylradical, optionally substituted with one or more hydroxyl groups, andpreferably a linear C₁ to C₆ alkyl group, optionally substituted with ahydroxyl group, such as a methyl, hexyl or hydroxyhexyl group. 3.Process according to claim 1, characterized in that R₄ and R′₄, whichmay be identical or different, represent: an amino radical, or a radical—NR₅R₆, in which R₅ and R₆, which may be identical or different,represent, independently of each other: a linear or branched C₁ to C₆and more preferentially C₁ to C₄ alkyl radical, optionally substitutedwith one or more hydroxyl groups, or a phenyl radical.
 4. Processaccording to claim 1, characterized in that the dye(s) (a) are chosenfrom the compounds of formula (I) or (II) in which: R₃ and R′₃, whichmay be identical or different, represent, independently of each other: aC₁ to C₂ alkyl radical, an amino radical, an acylamino radical(—NHCOCH₃), a chlorine atom, a C₁ to C₂ alkoxy radical, oralternatively, two adjacent radicals R₃ or R′₃ together form a6-membered aromatic ring optionally substituted with a hydroxyl or aminogroup, or alternatively, two radicals R₃ of formula (I) or R′₃ offormula (II) located, respectively, ortho to the group R₄ (formula (I))or R′₄ (formula (II)) form, respectively, with R₅ and R₆ of the group R₄(formula (I)) or of the group R′₄ (formula (II)) a 6- to 10-memberedheterocycle comprising one or two heteroatoms such as nitrogen,preferably the phenyl group substituted with R₃ and R₄ or R′₃ and R′₄represents ajulolidine group; and R₄ and R′₄, which may be identical ordifferent, represent: an amino radical, or a radical —NR₅R₆, in which R₅and R₆, which may be identical or different, represent, independently ofeach other: a linear or branched C₁ to C₄ alkyl radical, optionallysubstituted with one or more hydroxyl groups, or a phenyl radical. 5.Process according to claim 1, characterized in that the 2- or4-azopyridinium dye(s) (a) are chosen from the following compounds, theoptical isomers thereof, the geometrical isomers thereof, the tautomersthereof, the organic or mineral, acid or base salts thereof, thesolvates thereof such as hydrates, and mixtures thereof:

Y being as defined in claim
 1. 6. Process according to claim 1,characterized in that the fluorescent dye(s) (b) are chosen from thefollowing dyes: acridines, acridones, azlactones, benzanthrones,benzimidazoles, benzimidazolones, benzindoles, benzoxazoles,benzopyrans, benzothiazoles, coumarins,difluoro{2-[(2H-pyrrol-2-ylidene-kN)methyl]-1H-pyrrolato-kN}borons,dipyrinones, diketopyrrolopyrroles, fluorindines, (poly)methines(especially cyanins and styryls/hemicyanins), naphthalimides,naphthanilides, naphthylamine (such as dansyls), naphtholactams,oxadiazoles, oxazines, perilones, perinones, perylenes,polyenes/carotenoids, squaranes, stilbenes, xanthenes, thioxanthenes,thiazines, and mixtures thereof, and, preferably, the fluorescent dye(s)are cationic.
 7. Process according to claim 1, characterized in that thefluorescent dye(s) (b) are direct dyes; preferably, the fluorescentdye(s) are direct dyes chosen from (poly)methine dyes, in particularcyanin dyes and styryl/hemicyanin dyes, and naphthalimide dyes, andmixtures thereof; more preferentially, the fluorescent dyes are directand cationic and are chosen from styryl or hemicyanin cationic dyes. 8.Process according to claim 1, characterized in that the fluorescentdye(s) (b) are dyes which absorb light in the yellow, orange and redrange, preferably in the absorption wavelength λ_(abs) between 400 nmand 500 nm inclusive.
 9. Process according to claim 1, characterized inthat the fluorescent dye(s) (b) are dyes which comprise at least onecationic chromophore chosen from formulae (III), (IV), (IIIa) and (IVa)below:W⁺—[C(R^(c))═C(R^(d))]_(m′)—Ar′—(*)Q⁻  (III)Ar—[C(R^(d))═C(R^(c))]_(m′),W′⁺—(*)Q⁻  (IV), in which formulae (III) and(IV): W⁺ represents a cationic heteroaryl group, in particularcomprising a quaternary ammonium optionally substituted with one or more(C₁-C₈)alkyl groups optionally substituted in particular with one ormore hydroxyl groups; W′⁺ represents a divalent heteroaryl radical asdefined for W⁺; Ar represents an aryl group such as phenyl or naphthyl,optionally substituted preferably with i) one or more halogen atoms suchas chlorine or fluorine; ii) one or more (C₁-C₈)alkyl and preferablyC₁-C₄ alkyl groups such as methyl; iii) one or more hydroxyl groups; iv)one or more (C₁-C₈)alkoxy groups such as methoxy; v) one or morehydroxy(C₁-C₈)alkyl groups such as hydroxyethyl, vi) one or more aminoor (di)(C₁-C₈)alkylamino groups, preferably with the C₁-C₄ alkyl partoptionally substituted with one or more hydroxyl groups, such as(di)hydroxyethylamino, vii) with one or more acylamino groups; viii) oneor more heterocycloalkyl groups such as piperazinyl, piperidyl or 5- or6-membered heteroaryl such as pyrrolidinyl, pyridyl and imidazolinyl;Ar′ is a divalent aryl radical as defined for Ar; m′ represents aninteger between 1 and 4 inclusive, in particular, m′ is 1 or 2; betterstill 1; R^(c) and R^(d), which may be identical or different, representa hydrogen atom or optionally a substituted (C₁-C₈)alkyl and preferablyC₁-C₄ alkyl group, or alternatively R^(c) is contiguous with W or W′and/or R^(d) is contiguous with Ar or Ar′ and form, with the atoms thatbear them, a (hetero)cycloalkyl; in particular, R^(c) is contiguous withW⁺ or W′⁺ and forms a (hetero)cycloalkyl such as cyclohexyl; Q⁻ is anorganic or mineral anionic counterion; (*) represents the part of thefluorescent chromophore that is bonded to the rest of the dye;preferably, W⁺ or W′⁺ is an imidazolium, pyridinium, benzimidazolium,pyrazolium, benzothiazolium or quinolinium radical optionallysubstituted with one or more identical or different C₁-C₄ alkylradicals; preferably, the fluorescent chromophore(s) are chosen fromthose with m′=1, Ar representing a phenyl group substituted para to thestyryl group —C(R^(d))═C(R^(c))—with a (di-)(hydroxy)(C₁-C₆)(alkyl)aminogroup such as dihydroxy(C₁-C₄)alkylamino, and W′⁺ representing animidazolium or pyridinium group, preferably ortho- or para-pyridinium;

in which formulae (IIIa) and (IVa) R^(e), R^(f), R^(g) and R^(h), whichmay be identical or different, represent a hydrogen atom or a(C₁-C₆)alkyl group which is optionally substituted, preferentially witha di(C₁-C₆)alkylamino or tri(C₁-C₆)alkylammonium group such astrimethylammonium.
 10. Process according to claim 1, characterized inthat the fluorescent dye(s) (b) are chosen from the dyes of formulae(V), (VI) and (VII) and also the organic or mineral, acid or base saltsthereof, the optical isomers, geometrical isomers and tautomers thereof,and the solvates thereof such as hydrates:

in which formulae (V), (VI) and (VII): R₁ and R₂, which may be identicalor different, represent a hydrogen atom or a C₁-C₆ alkyl group;preferentially a hydrogen atom; G₁ represents a hydrogen atom or a groupchosen from NH₂ and OH; R_(a), R′_(a), R″_(a), R″′_(a), R_(b), R′_(b),R″_(b) and R″′_(b), which may be identical or different, represent a) ahydrogen atom, b) a halogen atom, a group from among: c) amino, d)(C₁-C₄)alkylamino, e) (C₁-C₄)dialkylamino, f) cyano, g) carboxyl —C(O)OHor carboxylate —C(O)O⁻, Q⁺, h) hydroxyl —OH or alkoxide —O⁻Q⁺, i)(poly)halo(C₁-C₆)alkyl such as trifluoromethyl, j) acylamino, k)(C₁-C₆)alkoxy, 1) (C₁-C₆)alkylthio, m) (poly)hydroxy(C₂-C₄)alkoxy, n)(C₁-C₆)alkylcarbonyloxy, o) (C₁-C₆)alkoxycarbonyl, p)(C₁-C₆)alkylcarbonylamino, q) acylamino, r) carbamoyl, s)(C₁-C₆)alkylsulfonylamino, t) aminosulfonyl, u) —SO₃H or sulfonate —SO₃⁻, Q⁺ or v) (C₁-C₆)alkyl optionally substituted with a group chosen from(C₁-C₆)alkoxy, hydroxyl, cyano, carboxyl, amino, (di)(C₁-C₄)alkylamino,or alternatively the two alkyl radicals borne by the nitrogen atom ofthe amino group form a 5- to 7-membered heterocycle optionallycomprising another nitrogen or non-nitrogen heteroatom; in particular,R_(a), R′_(a), R″_(a), R′″_(a), R_(b), R′_(b), R″_(b) and R′″_(b)represent a hydrogen or halogen atom or a (C₁-C₄)alkyl group, preferablya hydrogen atom; or alternatively two groups R_(a) and R′_(a); R_(b) andR′_(b) borne by two adjacent carbon atoms together form a benzo orindeno ring, a fused heterocycloalkyl or fused heteroaryl group; thebenzo, indeno, heterocycloalkyl or heteroaryl ring being optionallysubstituted with a halogen atom, an amino, (C₁-C₄)alkylamino,(C₁-C₄)dialkylamino, nitro, cyano, carboxyl, hydroxyl or trifluoromethylgroup, an acylamino, (C₁-C₄)alkoxy, (poly)hydroxy(C₁-C₄)alkoxy,(C₁-C₄)alkylcarbonyloxy, (C₁-C₄)alkoxycarbonyl or(C₁-C₄)alkylcarbonylamino radical, an acylamino, carbamoyl oralkoxyalkylsulfonylamino radical, an aminosulfonyl radical, or a(C₁-C₆)alkyl radical optionally substituted with: a group chosen from(C₁-C₆)alkoxy, hydroxyl, cyano, carboxyl, amino, (C₁-C₄)alkylamino and(C₁-C₄)dialkylamino, or alternatively the two alkyl radicals borne bythe nitrogen atom of the amino group form a 5- to 7-membered heterocycleoptionally comprising another nitrogen or non-nitrogen heteroatom;preferentially, R_(a) and R′_(a) together form a benzo group; oralternatively, two groups R_(i) and R_(a); and/or a group R′_(i) andR′_(a) together form a fused (hetero)cycloalkyl, preferentiallycycloalkyl such as cyclohexyl; R_(g) represents a hydrogen atom, a(hetero)aryl(C₁-C₄)alkyl group or a (C₁-C₆)alkyl group that isoptionally substituted; preferentially, R_(b) represents a hydrogen atomor a (C₁-C₃)alkyl or benzyl group; R_(e) represents a covalent bond, alinear or branched, optionally substituted (C₁-C₈)alkylene or(C₂-C₈)alkenylene hydrocarbon-based chain, preferably R_(e) representsan unsubstituted (C₁-C₆)alkylene; R_(f) represents a hydrogen atom, a(C₁-C₄)alkoxy group, an amino group R₃R₄N—, a quaternary ammonium groupM′, R₃R₄R₅N⁺— in which R₃, R₄ and R₅, which may be identical ordifferent, represent a (C₁-C₄)alkyl group or R₃R₄N— represents anoptionally substituted heteroaryl group, preferentially an optionallysubstituted imidazolyl group, or alternatively M′, R₃R₄R₅N⁺— representsan optionally substituted cationic heteroaryl group, preferentially animidazolinium group optionally substituted with a (C₁-C₃)alkyl group; Grepresents i) a group —NR_(c)R_(d), ii) —OR with R representing a) ahydrogen atom, b) an optionally substituted, preferentiallyunsubstituted (C₁-C₆)alkyl group, c) an optionally substituted(hetero)aryl group, d) an optionally substituted(hetero)aryl(C₁-C₆)alkyl group such as benzyl, e) optionally substituted(hetero)cycloalkyl, f) optionally substituted(hetero)cycloalkyl(C₁-C₆)alkyl; according to a particular embodiment, Grepresents a group —NR_(c)R_(d), according to another particularembodiment, G represents a (C₁-C₆)alkoxy group; or alternatively when Grepresents —NR_(c)R_(d), two groups R_(c) and R′_(a) and/or R_(d) andR_(a) together form a saturated heteroaryl or heterocycle, optionallysubstituted with one or more (C₁-C₆)alkyl groups, preferentially a 5- to7-membered heterocycle containing one or two heteroatoms chosen fromnitrogen and oxygen; more preferentially, the heterocycle is chosen frommorpholinyl, piperazinyl, piperidyl and pyrrolidinyl groups; R_(c) andR_(d), which may be identical or different, represent a hydrogen atom ora group from among: a) optionally substituted (hetero)aryl such asphenyl, b) optionally substituted (hetero)aryl(C₁-C₄)alkyl, c)optionally substituted (hetero)cycloalkyl, d) optionally substituted(hetero)cycloalkyl(C₁-C₄)alkyl, f) (C₂-C₅)alkyl or g) (C₁-C₈)alkyl whichis optionally substituted, preferably optionally substituted with ahydroxyl, carboxyl, carboxylate, sulfate or sulfonate group; oralternatively two adjacent radicals R_(c) and R_(d) borne by the samenitrogen atom together form an optionally substituted heterocyclic oroptionally substituted heteroaryl group; R_(i) and R′_(i), which may beidentical or different, represent a hydrogen atom or a (C₁-C₄)alkylgroup;

represents a (hetero)aryl group fused to the phenyl ring; oralternatively is absent from the phenyl; preferentially, when the ringis present, the ring is a benzo; m represents an integer between 1 and18 inclusive, particularly an integer between 1 and 14 inclusive;preferentially an integer between 2 and 10 inclusive; morepreferentially an integer between 3 and 8; more particularly an integerbetween 4 and 6; M′ represents an anionic counterion, derived from asalt of an organic or mineral acid, or from an organic or mineral basethat ensures the electrical neutrality of the dye; Q⁺ represents acationic counterion, derived from a salt of an organic or mineral acid,or from an organic or mineral base that ensures the electricalneutrality of the dye such as alkali metal, alkaline-earth metal orammonium; it being understood that when the dye comprises a carboxylate,sulfonate or alkoxide group, then M′ and Q⁺ may be absent to ensure theelectrical neutrality of said dye.
 11. Process according to claim 1,characterized in that the fluorescent dye(s) (b) are chosen from thestyryl dyes of formula (VIII) below, and also the organic or mineral,acid or base salts thereof, the optical isomers, geometrical isomers andtautomers thereof, and the solvates thereof such as hydrates:

in which formula (VIII) G, G₁, R_(a), R′_(a), R″_(a), R_(b), R′_(b),R″_(b), R_(i), R′_(i), R₁, R₂ and m are as defined in the precedingclaim; preferably: R₁ and R₂, which may be identical or different,represent a hydrogen atom; R₁ and R_(i′), which may be identical ordifferent, represent a hydrogen atom or a (C₁-C₄)alkyl group, preferablyhydrogen; R_(a), R′_(a) and R″_(a), which may be identical or different,represent a hydrogen atom, a halogen atom such as fluorine, or an —OH,—O⁻Q⁺, (C₁-C₆)alkoxy, nitro, or cyano group, with Q⁺ as defined in thepreceding claim; R_(b), R′_(b) and R″_(b), which may be identical ordifferent, represent a hydrogen atom or a (C₁-C₆)alkyl group; oralternatively two contiguous radicals R_(b) and R′_(b) form, togetherwith the carbon atoms that bear them, a benzo group that is condensed orfused to the pyridinium group, said benzo group possibly beingsubstituted; preferably, said benzo group is unsubstituted; G representsa group —NR_(c)R_(d) or (C₁-C₆)alkoxy group which is optionallysubstituted, preferentially unsubstituted; according to a particularembodiment, G represents a group —NR_(c)R_(d), according to anotherparticular embodiment, G represents a (C₁-C₆)alkoxy group; R_(i) andR′_(i), which may be identical or different, represent a hydrogen atomor a (C₁-C₄)alkyl group;

represents an aryl or heteroaryl group fused to the phenyl ring; oralternatively is a sent from the phenyl ring; preferentially, when thering is present, the ring is a benzo; m represents an integer between 1and 18 inclusive; particularly an integer between 2 and 16 inclusive;preferentially an integer between 3 and 10; more preferentially aninteger between 4 and 6; R_(c) and R_(d), which may be identical ordifferent, represent a hydrogen atom, a (C₂-C₄)alkyl group or asubstituted (C₁-C₈)alkyl group, preferably (C₂-C₄)alkyl substituted inparticular with one or more groups chosen from i) cyano, ii)(C₁-C₃)alkoxy, iii) hydroxyl and iv) (C₁-C₃)alkylcarbonyl, preferablywith one or more hydroxyl groups; and M′ representing an anioniccounterion, derived from a salt of an organic or mineral acid, or froman organic or mineral base that ensures the electrical neutrality of thedye; it being understood that when the dye comprises an alkoxide group,then M′ and Q⁺ may be absent to ensure the electrical neutrality of saiddye.
 12. Process according to claim 1, characterized in that thefluorescent dye(s) (b) are chosen from the styryl dyes of formula (IX)below, and also the organic or mineral, acid or base salts thereof, theoptical isomers, geometrical isomers and tautomers thereof, and thesolvates thereof such as hydrates:

in which formula (IX) G, G₁, R_(a), R′_(a), R_(b), R′_(b) and m are asdefined in either of claims 10 and
 11. 13. Process according to claim 1,characterized in that the fluorescent dye(s) (b) are chosen from thecompounds of formulae (X), (XI), (XII) and (XIII) below, and also theorganic or mineral, acid or base salts thereof, the optical isomers,geometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates:

in which formulae (X), (XI), (XII) and (XIII): R¹, R², R³ and R⁴, whichmay be identical or different, represent a hydrogen atom or a(C₁-C₆)alkyl group; preferably, R² and R³ represent a hydrogen atom andR¹ and R⁴, which may be identical or different, represent a hydrogenatom or a (C₁-C₄)alkyl group; R⁵, R⁶, R⁷, R⁸ and R⁹, which may beidentical or different, represent i) a hydrogen atom or ii) a halogenatom such as Cl, Br or F, iii) a group OR in which R represents ahydrogen atom or Q⁺ as defined in claim 10, or a (C₁-C₃)alkyl group, agroup from among iv) aryl such as benzene, v) aryl(C₁-C₃)alkyl such asbenzyl, vi) cyano, vii) nitro, viii) (C₁-C₃)alkylthio, ix) amino NR¹⁰R¹¹with R¹⁰ and R¹¹, which may be identical or different, representing a) ahydrogen atom, b) a (C₂-C₄)alkyl group or c) a substituted (C₁-C₈)alkylgroup, preferably (C₂-C₄)alkyl group optionally substituted with one ormore groups chosen from: cyano, (C₁-C₃)alkoxy, hydroxyl, and(C₁-C₃)alkylcarbonyl; in particular, R¹⁰ and R¹¹, which may be identicalor different, represent a hydrogen atom or a (C₁-C₆)alkyl groupsubstituted with one or more hydroxyl, cyano or (C₁-C₃)alkylcarbonylgroups such as hydroxyethyl; m represents an integer between 1 and 18inclusive; particularly an integer between 2 and 16 inclusive;preferentially an integer between 3 and 10; more preferentially aninteger between 4 and 6; M′ represents an anionic counterion as definedin claim 11; it being understood that when the dye comprises an alkoxidegroup, then M′ and Q⁺ may be absent to ensure the electrical neutralityof said dye.
 14. Process according to claim 1, characterized in that thefluorescent dye(s) (b) of the invention are chosen from those offormulae (XIV) and (XV) below:

in which formulae (XIV) and (XV) R⁵, R⁷, R⁸ and m are as defined inclaim 13, in particular: R⁵ and R⁸, which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkoxy group such as methoxy,preferably, R⁵ and R⁸ represent a hydrogen atom; R⁷ represents a(C₁-C₄)alkoxy group or NR¹⁰R¹¹ with R¹⁰ and R¹¹, which may be identicalor different, representing a) a hydrogen atom, or b) a (C₁-C₈)alkylgroup optionally substituted with one or more groups chosen from i)hydroxyl, ii) R—Z—C(X)—Y— with X, Y and Z representing an oxygen orsulfur atom or N(R′), or alternatively X and/or Z represent a bond, Rand R′, which may be identical or different, represent a hydrogen atomor a (C₁-C₆)alkyl group, preferably, X represents an oxygen atom, iii)sulfonic SO₃H, iv) sulfonate SO₃ ⁻, Q⁺, v) carboxylate C(O)O⁻, Q⁺ withQ⁺ representing a cationic counterion such as an alkali metal oralkaline-earth metal; in particular, R⁷ represents a group NR¹⁰R¹¹ withR¹⁰ and R¹¹, which may be identical or different, representing a) ahydrogen atom, or b) a (C₁-C₆)alkyl group optionally substituted withone or more groups chosen from i) hydroxyl, ii) carboxyl, iii)carboxylate, iv) sulfonic, and v) sulfonate, more particularly chosenfrom identical or different groups representing a) a hydrogen atom, orb) a (C₁-C₆)alkyl group optionally substituted with one or more groupschosen from i) hydroxyl, ii) carboxyl, and iii) carboxylate; mrepresents an integer between 1 and 18 inclusive; particularly aninteger between 1 and 6 inclusive; preferentially an integer between 1and 4; more preferentially an integer between 1 and 2; and M′ representsan anionic counterion, derived from a salt of an organic or mineralacid, or from an organic or mineral base that ensures the electricalneutrality of the dye; it being understood that when the dye comprisesan alkoxide group, then M′ and Q⁺ may be absent to ensure the electricalneutrality of said dye.
 15. Process according to claim 13, characterizedin that the fluorescent dye(s) (b) are chosen from: the fluorescent dyesof formula (X) with: R¹ R² R³ R⁴ R⁵ R⁶ R⁷ R⁸ R⁹ m H H H H H H H H H 1 HH H H H t-Bu OH t-Bu H 5 H H H H H t-Bu OH t-Bu H 5 H H H H H H NH₂ H H1 H H H H H H NH₂ H OCH₃ 1 H H H H H H OH Br H 5 H H H H H OCH₃ OH OCH₃H 5 H H H H Cl H OH H Cl 5 H H H H H H OH H H 10 H H H H H OCH₃ OH OCH₃H 10 H H H H H t-Bu OH t-Bu H 10 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H HH N(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H t-Bu OH t-Bu H10 H H H H H H N(CH₂CH₃)CH₂CH₂OH H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H HH H H H N(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H HN(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H H N(CH₂CH₃)₂ H H 1 H H H H H HN(CH₂CH₃)₂ H H 1 H H H H H H n-C₆H₁₃ H H 1 H H H H H H N(CH₂CH₂OH)₂ H H2 H H H H H H N(n-Bu)₂ H H 2 H H H H H OCH₃ OH H H 10 H H H H H HOC₂H₅OH H H 1 H H H H H H OH H H 1 H H benzo H H H H H 1 H H benzo H HN(CH₂CH₂OH)₂ H H 1 H H benzo H H N(CH₂CH₂OH)₂ H H 1

and also the organic or mineral, acid or base salts thereof, the opticalisomers, geometrical isomers and tautomers thereof, and the solvatesthereof such as hydrates; the fluorescent dyes of formula (XI) with: R¹R² R³ R⁴ R⁵ R⁶ R⁷ R⁸ R⁹ m CH₃ H H H OH H OCH₃ H H 2 CH₃ H H H H H OCH₃OCH₂—Ph H 2 CH₃ H H H H H H H OCH₃ 2 CH₃ H H H F H H H H 2 CH₃ H H H H HH OPh H 2 CH₃ H H H H H N(CH₂CH₂OAc)₂ H H 2 CH₃ H H H OCH₃ H OCH₃ OCH₃ H2 CH₃ H H H H H H CH₃ H 2 CH₃ H H H H H OH H H 2 CH₃ H H H H OCH₃ OCH₃OCH₃ H 2 CH₃ H H H H OCH₃ OH OH H 2 CH₃ H H H H H OCH₃ OCH₃ OCH₃ 2 CH₃ HH H H H H OCH₃ OH 2 CH₃ H H H H H N(n-butyl)2 H H 2 CH₃ H H H H OCH₃OCH₃ H H 2 CH₃ H H H H H H H H 2 CH₃ H H H H H i-propyl H H 2 H H H H HH OH H H 6 H H H H H OCH₃ OCH₃ OCH₃ H 6 H H H H OH H OCH₃ H H 2 H H H HOCH₃ H H OCH₃ OCH₃ 2 H H H H H H H H Br 2 H H H H H H OH H H 2 H H H HOCH₃ OCH₃ OCH₃ H H 6 H H H H OH OCH₃ H H H 6 H H H H H OCH₃ OCH₃ H H 6 HH H H H OCH₃ OCH₃ H H 2 H H H H H H C(O)—OH H H 6 H H H H H H C(O)—OH HH 2 H H H H H H i-propyl H H 2 H H H H H H N(CH₃)CH₂CH₂CN H H 2 H H H HH H OCH₃ OCH₂Ph H 2 H H H H H H H OPh H 2 H H H H H H N(CH₂CH₂C(O)CH₃)₂H H 2 H H H H OH H OCH₃ H H 6 H H H H H OCH₃ OCH₃ OCH₃ H 2 H H H H OCH₃H OCH₃ OCH₃ H 6 H H H H H H H CH₃ H 2 H H H H H H N(CH₃)CH₂CH₂OH H H 2

and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates; the fluorescent dyes of formulae (X′) and (XI′):

with M′ as defined in the preceding claim; and R⁵ R⁷ R⁸ m R⁵ R⁷ R⁸ m HN(CH₂CH₂OH)₂ H 2 OCH₃ OCH₃ OCH₃ 2 H N(CH₂CH₂OH)₂ H 3 OCH₃ OCH₃ OCH₃ 3 HN(CH₂CH₂OH)₂ H 4 OCH₃ OCH₃ OCH₃ 3 H N(CH₂CH₂OH)₂ H 5 OCH₃ OCH₃ OCH₃ 4 HN(CH₂CH₂OH)₂ H 6 OCH₃ OCH₃ OCH₃ 5 H N(CH₂CH₂OH)₂ H 8 OCH₃ OCH₃ OCH₃ 8 HN(CH₂CH₂OH)₂ H 10 OCH₃ OCH₃ OCH₃ 10 H N(CH₂CH₂OH)₂ H 12 OCH₃ OCH₃ OCH₃12 H N(CH₂CH₂OH)₂ H 14 OCH₃ OCH₃ OCH₃ 14 H N(CH₂CH₂OH)₂ H 16 OCH₃ OCH₃OCH₃ 16 H CH₃CH₂N(CH₂CH₂OH) H 2 H CH₃CH₂N(CH₂CH₂OH) H 4 and

and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates; the fluorescent dyes of formula (XII) with: R¹ R² R³ R⁴ R⁵R⁶ R⁷ R⁸ R⁹ m H H H H H H OCH₃ OCH₃ OCH₃ 2 H H H H OH OCH₃ H H H 2 H H HH H H H H H 2 H H H H H OCH₃ OCH₃ H H 2 H H H H OH H OH H H 6 H H H HOCH₃ H OCH₃ OCH₃ H 6 H H H H H H OH H H 6 H H H H OCH₃ H H H F 2 H H H HH H C(O)—OH H H 2 H H H H H H Isopropyl H H 2 H H H H H HN(CH₂CH₂C(O)CH₃)₂ H H 2 H H H H OH H OCH₃ H H 2 H H H H H H OH H H 2 H HH H H OCH₃ OH OH H 2 H H H H H CH₃ OCH₂Ph CH₃ H 2 H H H H H OCH₃ OCH₃OCH₃ H 2 H H H H H OCH₃ OCH₃ OCH₃ H 6 H H H H H H N(CH₃)₂ H H 6 H H H HH H OCH₃ OCH₃ OCH₃ 6 H H H H H H Phenyl H H 6 H H H H H OCH₃ OCH₃ H H 6H H H H H H C(O)—OH H H 6 H H H H H H N(n-Butyl)₂ H H 2 H H H H H H OCH₃OCH₃ H 3 H H H H H H OCH₃ OCH₃ H 2 H H H H H H OCH₃ OCH₃ H 5 H H H H H HOCH₃ H H 3 H H H H H H N(CH₃)₂ H H 3 H H H H H H H H H 3

and also the organic or mineral, acid or base salts thereof, the opticalisomers, geometrical isomers and tautomers thereof, and the solvatesthereof such as hydrates; the fluorescent dyes of formula (XIII) with:R¹ R² R³ R⁴ R⁵ R⁶ R⁷ R⁸ R⁹ m CH₃ H H H OH H OCH₃ H H 2 CH₃ H H H H HOCH₃ OCH₂—Ph H 2 CH₃ H H H H H H H OCH₃ 2 CH₃ H H H F H H H H 2 CH₃ H HH H H H OPh H 2 CH₃ H H H H H N(CH₂CH₂OAc)₂ H H 2 CH₃ H H H OCH₃ H OCH₃OCH₃ H 2 CH₃ H H H H H H CH₃ H 2 CH₃ H H H H H OH H H 2 CH₃ H H H H OCH₃OCH₃ OCH₃ H 2 CH₃ H H H H OCH₃ OH OH H 2 CH₃ H H H H H OCH₃ OCH₃ OCH₃ 2CH₃ H H H H H H OCH₃ OH 2 CH₃ H H H H H N(n-butyl)₂ H H 2 CH₃ H H H HOCH₃ OCH₃ H H 2 CH₃ H H H H H H H H 2 CH₃ H H H H H i-propyl H H 2 H H HH H H OH H H 6 H H H H H OCH₃ OCH₃ OCH₃ H 6 H H H H OH H OCH₃ H H 2 H HH H OCH₃ H H OCH₃ OCH₃ 2 H H H H H H H H Br 2 H H H H H H OH H H 2 H H HH H H N(CH₃)₂ H H 6 H H H H OCH₃ OCH₃ OCH₃ H H 6 H H H H OH OCH₃ H H H 6H H H H H OCH₃ OCH₃ H H 6 H H H H H OCH₃ OCH₃ H H 2 H H H H H H C(O)—OHH H 6 H H H H H H C(O)—OH H H 2 H H H H H H i-propyl H H 2 H H H H H HN(CH₃)CH₂CH₂CN H H 2 H H H H H H OCH₃ OCH₂Ph H 2 H H H H H H H OPh H 2 HH H H H H N(CH₂CH₂C(O)CH₃)₂ H H 2 H H H H OH H OCH₃ H H 6 H H H H H OCH₃OCH₃ OCH₃ H 2 H H H H OCH₃ H OCH₃ OCH₃ H 6 H H H H H H H CH₃ H 2 H H H HH H N(CH₃)CH₂CH₂OH H H 2 CH₃ H H H H H N(CH₃)₂ H H 2

and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates; and the fluorescent dyes of formulae (XII′) and (XIII′)below:

with: R⁵ R⁷ R⁸ m: R⁵ R⁷ R⁸ m H N(CH₂CH₂OH)₂ H 2 OCH₃ OCH₃ OCH₃ 2 HN(CH₂CH₂OH)₂ H 3 OCH₃ OCH₃ OCH₃ 3 H N(CH₂CH₂OH)₂ H 4 OCH₃ OCH₃ OCH₃ 3 HN(CH₂CH₂OH)₂ H 5 OCH₃ OCH₃ OCH₃ 4 H N(CH₂CH₂OH)₂ H 6 OCH₃ OCH₃ OCH₃ 5 HN(CH₂CH₂OH)₂ H 8 OCH₃ OCH₃ OCH₃ 8 H N(CH₂CH₂OH)₂ H 10 OCH₃ OCH₃ OCH₃ 10H N(CH₂CH₂OH)₂ H 12 OCH₃ OCH₃ OCH₃ 12 H N(CH₂CH₂OH)₂ H 14 OCH₃ OCH₃ OCH₃14 H N(CH₂CH₂OH)₂ H 16 and OCH₃ OCH₃ OCH₃ 16

and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates; and preferably, the fluorescent dye(s) (b) are chosen fromthe following compounds:

and also the organic or mineral, acid or base salts thereof, thegeometrical isomers and tautomers thereof, and the solvates thereof suchas hydrates; with M′ and Q⁺ as defined in the preceding claim. 16.Process according to claim 1, characterized in that it also comprisesthe application to said keratin fibres of one or more reducing agents,preferably chosen from i) the reducing agents of formula (XVI) below,and also the addition salts thereof, and mixtures thereof:H(X)_(q)(R₁₀)_(t)  (XVI) in which formula (XVI): X represents P, S orSO₂, q represents an integer equal to 0 or 1, t represents an integerequal to 1 or 2, and R represents a linear or branched, saturated orunsaturated C₁ to C₂₀ alkyl radical, optionally interrupted with aheteroatom, and/or optionally substituted with one or more radicalschosen from hydroxyl, halo, amine, carboxyl, ((C₁-C₃₀)alkoxy)carbonyl,amido, ((C₁-C₃₀)alkyl)aminocarbonyl, ((C₁-C₃₀)acyl)amino, mono- ordialkylamino, and mono- or dihydroxylamino radicals; ii) thioglycolicacid, iii) thiolactic acid, iv) glyceryl monothioglycolate, v)cysteamine, vi) N-acetylcysteamine, vii) N-propionylcysteamine, viii)cysteine, ix) N-acetylcysteine, x) thiomalic acid, xi) pantetheine, xii)2,3-dimercaptosuccinic acid, xiii)N-(mercaptoalkyl)-ω-hydroxyalkylamides, xiv) N-mono- orN,N-dialkylmercapto-4-butyramides, xv) aminomercaptoalkylamides, xvi)N-(mercaptoalkyl)succinamic acid derivatives, xvii)N-(mercaptoalkyl)succinimide derivatives, xviii) alkylaminomercaptoalkylamides, xix) the azeotropic mixture of 2-hydroxypropylthioglyconate and of (2-hydroxy-1-methyl)ethyl thioglycolate, xx)mercaptoalkylaminoamides, xxi) N-mercaptoalkylalkanediamides, xxii)formamidinesulfinic acid derivatives, addition salts thereof, andmixtures thereof.
 17. Process according to claim 1, characterized inthat it does not use any reducing agent.
 18. Process according to claim1, characterized in that the 2- or 4-azopyridinium dye(s) and thefluorescent dye(s) are applied together to said keratin fibres;preferably, the process comprises a step of applying to said keratinfibres a cosmetic composition which comprises one or more 2- or4-azopyridinium dyes (a) chosen from the compounds of formula (I) or(II), and also the optical isomers thereof, the geometrical isomersthereof, the tautomers thereof, the organic or mineral, acid or basesalts thereof, the solvates thereof such as hydrates, and mixturesthereof, and one or more fluorescent dyes.
 19. Process according toclaim 1, characterized in that it comprises at least the following twosuccessive steps: a first step of applying to said keratin fibres acosmetic composition comprising one or more fluorescent dyes followed bya second step of applying to said fibres a cosmetic compositioncomprising one or more 2- or 4-azopyridinium dyes (a) chosen from thecompounds of formula (I) or (II), and also the optical isomers thereof,the geometrical isomers thereof, the tautomers thereof, the organic ormineral, acid or base salts thereof, the solvates thereof such ashydrates, and mixtures thereof.
 20. Process according to claim 1,characterized in that it comprises at least the following two successivesteps: a first step of applying to said keratin fibres a cosmeticcomposition comprising one or more 2- or 4-azopyridinium dyes (a) chosenfrom the compounds of formula (I) or (II) as defined in any one ofclaims 1 to 5, and also the optical isomers thereof, the geometricalisomers thereof, the tautomers thereof, the organic or mineral, acid orbase salts thereof, the solvates thereof such as hydrates, and mixturesthereof, followed by a second step of applying to said fibres a cosmeticcomposition comprising one or more fluorescent dyes.
 21. Processaccording to claim 19, characterized in that it comprises at least twosuccessive steps in which the pH of the cosmetic composition(s) isbetween 6 and 11 inclusive, preferably between 7 and 10, morepreferentially between 7.5 and 9.5 and better still between 9 and 9.5.22. Cosmetic composition comprising one or more 2- or 4-azopyridiniumdyes (a) chosen from the compounds of formula (I) or (II), and also theoptical isomers thereof, the geometrical isomers thereof, the tautomersthereof, the organic or mineral, acid or base salts thereof, thesolvates thereof such as hydrates, and mixtures thereof, and one or morefluorescent dyes (b), said composition optionally having a pH of between6 and 11 inclusive, preferably between 7 and 10, more preferentiallybetween 7.5 and 9.5 and better still between 9 and 9.5. 23.Multi-compartment device comprising a first compartment containing oneor more 2- or 4-azopyridinium dyes (a) chosen from the compounds offormula (I) or (II), and also the optical isomers thereof, thegeometrical isomers thereof, the tautomers thereof, the organic ormineral, acid or base salts thereof, the solvates thereof such ashydrates, and mixtures thereof, and a second compartment containing oneor more fluorescent dyes (b).
 24. Use of one or more fluorescent dyes(b), combined with one or more 2- or 4-azopyridinium dyes (a) chosenfrom the compounds of formula (I) or (II), and also the optical isomersthereof, the geometrical isomers thereof, the tautomers thereof, theorganic or mineral, acid or base salts thereof, the solvates thereofsuch as hydrates, and mixtures thereof, for the dyeing of light keratinfibres, especially human keratin fibres such as the hair, inchestnut-brown, dark chestnut-brown, brown, brown with a glint or evenblack, without using an additional dye other than (a) or (b).